Neil,
I have a 1940 Chevy, so I don't know if it is the same. But I had a similar problem with my truck. I switched to a 1960 235 and a T-5 transmission. I wanted to keep the original pedals.
If you look at my t-5 rebuild page way at the bottom you will see my solution.
http://home.twcny.rr.com/schickling/1940Chevy/T5.html The bellhousing comes from Buffalo Enterprises. This may or may not work on your engine. If not maybe Buffalo Enterprises makes a similar one for GMC. I'm pretty sure they have a web page with at least a number to call.
Bill Schickling
