I would think a 3.55 gear may even work well with the 5 speed trans if you get there.
In my 1950 chev truck the saginaw trans bolted up easy. I modified the shifter so it moved forward on the trans several inches.
A T-350 trans may make the truck a little mellow of a driver. All depends on what is wanted.
That truck sounds like a blast. Any pictures?
AutoGear... I have no photos of the truck on this computer. I think there are some photos still on Inliners.org ... easy to find my 50 chev truck. Color was pink, with black top of the cab.