Since the track width is so narrow on the older trucks, most people use the S10 series truck chassis for this conversion. It keeps the tires inside the fenders where they belong, Scott
There is a fella in my home town that has done this exact thing. Put it on a fullsize 73-87 frame,track width is a little wide, but he is running big tires. He said all he did was mount the 46 body mounts to the latter frame.
i done 2 a 1946 chevy on a 1977 chevy short bed , 1946 gmc on a 1975 chevy long bed frame it is easy . alot of people use these frames . if someone has parts for a 1941-46 chevy/gmc just email me .i am looking for some . thanks