The RX7s were always very competent sports cars, and at ~2,400 lbs, would probably be a few hundred lbs lighter than a stock 4cyl capri & have a few more HP to boot. Nice RX7s are fetching good $ these days Royce. Not as much as this one off, celebrity tuner build, but they compare well to comparable fox body offerings.
Not true take a 1980 Miata and assemble a comparable team and budget to modify it like they did the Capri and my money would be on the Miata although I would rather see the mercury winning.
In the comments it stated the car sold at mecum in 2019 $56,100 add in the buying fees and the selling fees I would say the current seller lost over $10,000 not what I would call a good classic car investment. Still lots of 40 yr old Miata around they have a big cult following and I can’t go to a track event without seeing a few on the track at every event. I would much rather buy your 68 1/2 Cougar as I’m sure there would be some profit if I sold it 3 years later.
“This car sold at Mecum 2019 for $56,100.00. Hard to see it doing it again.”
Monster Miata pop up on Ebay off & on with the Ford v8 or Chevy LS installed. I have yet to see a V8 version on the track. it would be interesting to see how it performs with more weight in front. NASA has a spec Miata class and I’ve ran with them during their practice day at Grattan. Most fun I’ve had on a track as we go wheel to wheel. They have to limit the hp but spend money on suspension and handling. The cobalt is faster but some of them come close. The ones that go the extra mile on prep stand out. They have some really good drivers in that class that are usually on their way to pro status.
I have seen many different engines swapped in to Miatas. From 5.0 with a 6 speed to LS engines. One of the sweetest was a Buick 215 Aluminum block V8. Custom built EFI and crank fire ignition. That engine is a little more compact then a 302 and fit better then a LS. And with the weight of that engine the owner reported the handling was superb.