I run a built 250 in a 41 plymouth with a 700r4, when I first built it I had a 10"Gm with 3.08 gears (27" tires) to tall a gear caused a lot of shuttle shifting. Switched to a 9"ford with 3.50 gears much better I even tow my roadster with it, but if I wanted to do any serious quarter mile running I would go to 3.90 or 4.10. About ten years ago I built a T bucket for a fellow with a 350 and a 200r4 started with a low 3s rear gear then went to a 4.10 with a locker and it was unbelieveable the difference it made, felt like he added about 200 horses but with the overdrive it still cruised nicely down the highway at 70/75 mph.
