Could you share some pics...work in progress. I can appreciate your plan of attack...food for thought. If you plan on cruising allot an overdrive gear in say a Tremec sure is nice. 1st gear is lower than the Muncie, 4th gear is basically 1 to 1 like your Muncie, but 5th gear (overdrive) drops those rpm's significantly. Example, 350 sbc, Tremec 5-spd, with a 3:73 gear...cruising@ 70 mph....roughly 2000 rpm as opposed to 3000 rpm running a Muncie. Saves the motor and allot more enjoyable to drive. Still having that gear shift in hand.
