I just did this swap in my '61, with a '95 TBI, but I kept my transmission. If you have the whole truck, you're in great shape, and the swap won't be that tough.
For me, one of the biggest issue was motor mounts. I found a bellhousing on ebay, which kept my original rear mounts, but I had to make new front mounts. I probably could have bought a kit, but making my own was more fun.
Exhaust manifolds was the other biggie. Since mine is 3/4 ton, 4x4, I had a bit of trouble figuring out which ones to use. The '95 manifolds weren't even close, and a friend gave me a set of truck headers, but they didn't fit either. I ended up going with the original ram's horn style, which I picked up on ebay for like $50.
If you have a donor truck, wiring is actually quite simple. I hooked up all of 5 wires and had the thing running. 3 to the ignition switch, and 2 to the fuel pump. There's a few other little things, like guages, but other than that, it's pretty simple, if you take the whole engine harness out of the other truck. The computer is mounted on one end in the glove box area, then it goes through the firewall, around the back of the engine, and then to a fuse block near the brake pedal. One of the best things I ever bought when I did this swap was the Driveability, Emissions, and Diagnosis Manual. It has every wire, connector, and fuse labled, where to find it, pretty much everything. If you find one, buy it.
Fuel also presents a few more mods. I used a Holley Blue series electric pump, mounted in the frame rail. The only thing is it's really noisy. I'm sure you could find a different one that wouldn't be so loud. TBI only needs something like 13 to 14 psi, instead of 60+ for the later Vortec engines. Depending on what year your truck is, it might be a good time to move the tank out of the cab. I was going to do that, but time and finances started running a little low. Fabricating a return line can also prove challenging with an in-cab tank.
As far as the auto trans, can't say that I'd be much help. But, if you have the donor truck, you should have everything you need. That shop manual also has some info on transmissions.
I have to admit that I can't get much over 11 mpg since I did the swap. But, then again, I have 4.56 gears and a granny 4 speed. Also, I don't have the VSS hooked up, which I suspect may be the cause.
Keep me posted on how it goes, and feel free to ask me any questions. I'd be more than happy to give you any info I've got. I have bunch of pictures up on my webshots at the link below. I also have a bunch of links to places where I bought stuff. Have a good one...
