next question..would I be insane to mate the 350 wiht the 3spd tranny, provided I swap the rears to 3:7.3s??
I don't think so. That combination should work fine, and give decent mpg and relatively long engine life provided you don't do a lot of driving over 60 mph for extended periods of time.
I have a 1966 chevy pickup. I have the shortbed stepside model. It originally came with the 250/3 speed column combo. Mine has 3.73 rear gears. And with that combo I took it on
many 50-100+ mile trips driving 60-65 all the way. No problems whatsoever. 65 is the absolute maximum sustained speed that the engine was comfortable with. At that speed the engine was turning just under 3k. 2700 rpms at 60.
I swapped in a mildly built 292 (.060 over, 4 bbl, cam, headers, HEI, etc.) and a 4 speed overdrive trans. Now the truck will hold 75 mph with ease and it absolutely cruises at 70 turning only 2300 rpms.
For engine longevity, higher speed cruising possibilities and better mpg I recommend overdrive or a higher speed rear end (2.73-3.23 rear end ratio). If you go under 3.08 and want to keep a stick shift then I recommend going to a 4 speed.
-ftyler
