This is all way over my head, but if you could adapt a Mustang T5 (with the 3.35:1 first gear ratio), couldn't then expand to the Tremec replacements, including 6 spds?
Steve - yes with regards tremec parts. IMOH the 6-speed is very nice, but larger and heavier. My first gear ratio in my LT77 5 -speed was 3:24 - with dana 44 rear/3:08 gears - first was almost useless in my mgb. Also, the buick 215/rover 3.5 are like a brazilian cliff diver at 4500 with oem cam/heads - cam needs more lift/duration and some ported heads to run out those type of first gears. The ford T5 has 10 splines on input shaft - this would have to be changed to gm and an adapter for bell housing too - not sure if anyone makes one - so, would have to be custom piece. Yep, there sure seems to be a lot of Mustang T5's listed. Need to call Mark at D&D on Monday if I can remember to!
Brent - your 62 looks real clean in pics - and shifter looks just right! Btw, here is a few pics of mine and why I'm enhancing performance.....