I did this type of engine swap several years ago on a '48 Chevy 1/2 ton p/u. I think I remember most of the details.
I replaced the rear crossmember where the bell housing mounts to the frame. The crossmember I used was out of a '54 Chevy p/u. It was a bolt-in with no modifications needed. I am not sure when the crossmembers changed but the '48 and '54 were different.
The V8 bellhousing I used was from a late fiftys or early sixties p/u, I am sorry I don't remember exactly. There are several years that will let the small block engine, the crossmember and the stock '48 transmission all bolt up with no problems.
You will need to buy or make up some front motor mounts. Several companies that supply parts for street rods probably have some that you can use.
For clearance between the steering column and engine, I made spacers to place between the frame and the steering box. The column was angled slightly but after adjusting the toe-in it worked well.
I had trouble with the shift linkage on the steering column, so I went with a custom floor shifter. I later went with a stock four-speed.
For exhaust I used '56 Chevy passenger car manifolds. Today they may be hard to find but I believe block hugger headers would work fine.
Lots of people told me that the stock transmission, rearend and brakes would not hold up to the V8 power. I drove my truck for years and towed a camping trailer often. The only problem I had was a u-joint went out once.
Good luck with it and let me know if I left out any important details.
