If you're planning on towing the TH350 or the TH700R4 aren't the best choice. You would be best to try to find a 4L80E, or if you want to stick with a 3 speed use a TH400. TH350 is a great tranny but you might want something a bit more robust for towing.
If you're wanting to have something with all the creature comforts, why not try finding a wrote-off 2000-UP suburban that you can take the drivetrain, interior, etc. out of? I've seen them up here with leather and all, 5.3, OD., you could use the factory fuel injection and all. I've seen some for decent prices.
