Just thinking out load here. what shifter are you planning to use. The Muncie had several different tailshafts depending on the application, most position the shifter too far back to use with a bench seat. I ran into this issue while mocking up the Muncie for my '59, the shifter would have been at the floor brace for the seat. I found a company that deals with Muncie and talked with one of their Tech Reps. It turns out that the tailshaft I had would work with one of their relocation kits. The kit was cheap, installing it moved the shifter forward about 4 inches to front of the tailshaft. Take a minute and check out their site, GM Classic.com.
https://gmclassics.com/
