Your ignition timing sounds pretty good. However, pinging says there is something a bit off.
You’ve been at this a while. However, you still need to do further testing and charting out timing curve at 500 rpm intervals with your timing light to know where the timing actually is at what rpm. What vac levels does your advance start to pull and top out? Run a vacuum gauge in your car or tape it to the windshield. Then pay attention to at what rpm your engine pings and whether your vacuum advance was being pulled or if it didn’t matter because engine vacuum was below your “start vacuum”. If you plug the vac advance, does it still ping on the highway? If so, you may want to take a few degrees out of the vac.
The replacement cam specs you mentioned of 215-225 with a 111 lobe sep is about as much cam as what you currently have…since the current cam is 225/233 with a 113. The 113 is going to give you better idle characteristics than a 111. The lobes are not that aggressive. This is sometimes done to bleed off a little low end compression to help suppress detonation. Are your heads 2v open chamber? If so, and you reduce duration to help low end, it will ping worse. It’s funny how the closed chamber heads can run another point of compression on the same octane.
Your cam is moderate. It is by no means radical. It probably tops out at 5700-6000 rpm.
Lift has ZERO to do with your problems. You can reduce lift by putting on 1.5 or 1.6 rockers instead of the 1.73. Not sure if there is a rocker in that ratio that fits a 351c.
What temp is your thermostat? Does you engine run at that temp?
What RPM does the pinging on the highway happen? What gear are you in? Depending on the rpm you may need to tighten spring for mech curve and widen the vac range. Mechanical advance is solely based on rpm. Vacuum is dependent on engine load.
When the AOD is in 3rd or 4th it really harnesses down engine rpm exactly the same as a manual trans. It is a direct mechanical connection. No floating around rpms in a fluid connection like in 1st and 2nd. If shift timing is not set up correctly —for example if the cable is set too loose, it will be like driving in too high of a gear and not kick down for passing gear when sufficient throttle is applied. You would be better off to sway towards the cable being too tight for later shifts and easier kickdowns. Or change the governor for higher rpm shifts.
Go on ebay or Amazon and look for the book Dr. Jacobs Guide to Optimizing your Ignition. It’s from the 1980’s, but it’s not outdated for the procedure in finding the correct ignition curve for your engine in your vehicle.
Popping out of the carb is often referred to as a lean sneeze. There are probably other causes, like ignition crossfire or valve sealing that may promote popping. No vacuum leaks? Might be a stretch to consider doing a cylinder leak-down test. One thing that doesn’t take a lot of time is find a totally dark area to open you hood and look for spark leakage from the cap, wires and plugs. Let your eyes adjust for a bit. It’s surprising you can see the spark going through the porcelain plugs.
I’ve never used an Air Gap intake. My thought is carb temp is going to be hard to control. Heats up in traffic, cools off while cruising. Which do you tune for? Maybe this is where a self tuning EFI will help.
Hesitation on shifts. Are you talking the 1-2 shift? Or, 2-3? It is characteristic of the AOD to cause an engine to fall on it’s face on the 2-3 shift…because it totally takes away convertor stall. Higher shift points will help this.
You have a lot of stuff weighing in on this narrow balancing act. I say narrow because certain things will require tuning to be more spot-on than just being in the ball park. AOD, Air-Gap, moderate cam, compression on the edge of available octane. Glad you got rid of the 3.00 gear.
You’re kinda far. Too bad you weren’t coming to Carlisle. I’d like to road-test your Cougar.