Powerglide swap options.....
 

Took the car out on the Interstate for the first time today & at 70 mph +, she turns way too many rpms. I believe the rear is a 3.73 ( haven't raised the rear to count rotations yet ). My question is .....would a TH350 be any better with highway speed rpm's versus this 2 speed Powerglide? I realize there is no OD in the TH350 though. :confused:

Final output on all non overdrive transmissions is 1:1. There's no difference at all between them. As said above an overdrive trans or a higher ratio rear end are you best options.

I've been playing with the option of putting a 700 tranny in my 70, but they are fairly pricey but give you the overdrive. You will have to get the drive shaft shortened also.