Great pic Vic, have you had your car out this year ?
I will give you that, a race car with a narrow operating range in a race car needs a guy working the box and close ratio. However, you need the engine to pull the RPM to support the stiff gear, and on a street car, even that 4.11 is soft with SLR @ 9.32
I would add though, put that close ratio in a street small block with street gearing, a 3 speed will hand it it’s lunch off the line and the 4 speed will be fighting to catch up.
Regardless, your point is well-taken and should have mentioned that, like anything else, there is a right place for the combo. Also, incredibly cool car and awesome that you use it and run it hard too. Any details on the engine?
The current engine:
289+.030 custom BRC 12:1 pop-up pistons
289 block with stud girdle, windage tray, and crank scraper
D0OE 351W heads with 7/16" studs & guide plates, ported with 1.6/1.94 SS valves
C6ZZ-6B068-A dual-quad T/A intake
2-Holley 1848 465 CFM carbs
Group II Cougar-lettered oval air cleaner
Carter mechanical street/strip fuel pump
Crane mechanical cam 244/252 @.050, .553/.572 & spring kit
roller rockers
289 cast crank
H-beam rods with 7/16" bolts
Hooker Super Comp 1.625" headers
FMS roller timing chain
Hays aluminum flywheel
Romac aluminum balancer
Aviaid road-race oil pan
RPM range is 3500-7000
I haven’t been able to take it out this year. 
Back in the 80s 3.91s and 4.11s was the norm for quick street cars. We would drive all over and cruise down the highway. I have the stock 3.89s in my Shelby and stock 3.91s in the Eliminator. Cruising around on the roads is no sweat, but the highways these days it seems like traffic speed is about 80mph. So it is cruise in slow lane at 60mph @3000rpm and get blown by constantly, or step it up to almost 4000rpm to keep up with traffic. My 289Hipo like rpm but that’s a lot for the 428. So if I take the cars anywhere far it’s on the trailer it goes. Low gears are cool and fun, but you have use what is practical for the type of driving you plan to due. And going with a overdrive trans swap will add to the versatility of having a more fun rear gear and help mpg and drivability, unless you still want the originality of the car you have.
I just finished 4 FE strokers, street cars, ranging from 520 HP-570 HP, the two highest HP versions, and the lowest, had to keep vacuum at or above 15 inches. Then outlier is a Tunnel Wedge for a rowdy streetcar and was 546/546 but a bit more peaky
All except the Tunnel Wedge went OD and more gear. Not only for the OD itself, but 2 of them for the ability to have a much deeper 1st gear with the wider spread. The two manual tranny cars went with a TKO-600, one 3.91, one 4.11, the AT car is going with a modern Chevy electronically controlled 4 speed AT and a 3.89 gear. Although AT trannies don’t generally have a very deep 1st, the torque multiplication of the converter pre-stall acts similar, although a bit less efficient
The 4 speed TW engine, is going close ratio and 4.11s, but every chance I get I am trying to talk him into a wide ratio. Although I wouldn’t recommend a 3.50 gear for the TW car, right now, the 4.11 / CR combo is geared taller in 1st than a 3.50 /WR would be. I’d like to see the car with a WR and between 3.70 and 3.89 for the street/strip
Here is something you wouldn’t expect. I also run a TKO-600 in my EFI 489 FE and 4.11s, it had 3.70s originally as a holdover from the close ratio big in/out box I ran, the car was not significantly slower with the TKO/3.70 but it got worse mileage in town and on the highway, counter-intuitive, but like CougarsUnlimited high RPM 289, both rear end and transmission gears need to match the use.
I’m running 3.89 at the diff with a C6 and 25" tall tires. That means at 70 mph my engine will be turning at almost 3700RPM. Plans are to acquire a Gear Vendors OD in the near future, but for now the 3.89’s will work just fine for my daily commute and short cruises to the neighboring towns. Below is an engine RMP calculator that can help you think through what gears you want. Also know, that if you run 3.89 or 4.10 you will likely need a speedo gear adapter (link below) as they don’t make the correct speedo drive gears for the 3-speed automatics.
http://www.csgnetwork.com/multirpmcalc.html
https://speedometercablesusa.com/cables_and_housing_assembly.html
Thanks for posting the speedo parts/cable links!
I was running 4.10s. Once I built a motor capable of 2k+hp (currently 1238 on a 12# pulley) i switched to 3.25s for the obvious reason. Gearing is just about horsepower and usage.
There are a couple of reasons why not. 
Cougars are very light in the back. With the slightest bit of rain on the road, it just wants to do donuts. The 2nd gear is my best friend. I have a 68 with a decently built 302 and an 8" rear end. Even mustangs have light rear ends. The longer wheel base on Cougars makes it even worse.
I have no problems keeping up with traffic & the tires will even chirp a bit if I’m flooring it and going from 1st to 2nd gear. If you’re already getting sideways more often then you like, there’s zero need for more low end torque.
Cougars are heavier then other possible vehicles. If you’re going to drag race, a comet or first generation mustang is the better choice. Of course, the gear ratios would be aggressive for that.
On the other hand, if you want to tow a camper or small trailer, s larger classic car with a true body on frame design will hold up better.
Even without towing anything, some people think that the longer body is more likely to twist and distort if you put a lot of torque through it with a more aggressive set of gearing. I think that doing subframe connectors is practically mandatory in that scenario.
Cougars excel at cruising for long distances at high speeds across the country. I drove mine from Iowa down to Texas to see my girlfriend and then back to Baltimore. In Texas the speed limit is 80 mph and they don’t really enforce it much. Highway gears are best for that, not to mention gas mileage.
Cougars are set up more like a jaguar or a Mercedes in terms of what they do well. They’re more of a sport/luxury vehicle then a street strip vehicle. You don’t need or want aggressive gears for cross country road trips. My cougar is almost as smooth riding as a Cadillac and handles much better & I only have a stock suspension. A bigger sway bar would be nice to add.
What, in my opinion, would be best is to add a limited slip & get a larger fuel tank in order to balance the weight and increase the range you can drive. I think you might be able to get limited slip and keep the 8" original rear end but I’m not sure if you could do either. A limited slip would be the best upgrade & I’ll end up doing that if I can retain the same differential.