TB; I like your thinking!
However, 64, on your set-up,IMHO, it would not be cost effective in any way. I did just this swap on my 1980 Volare-fb in 95. Bumped the c/r to 9.0 as well, during a rebuild.I think the motor was a tad more responsive. No additional power. Maybe a hair better on gas. All-in-all I was disappointed. Your results may vary.I should maybe mention that I replaced the 80 motor with a 77 Super Six, that I had rebuilt to my specs. which included the 9.0 c/r, and one-size bigger mechanical cam kit. I waited what seemed like forever for the pistons.Ended up with 145psi cranking pressure.I woulda been better off swapping the rear end to 3.23s or maybe 3.55s. But yeah, 90 psi seems low. Just fine for low-performance, but the super six wont change much on your set-up.
If you decide to go for it anyway, make sure you get everything from the donor car.EVERYTHING, includes the gas pedal and cable.Others have tried to make it work with the floor mounted gas pedal. I think they mostly failed.
