Transmission deal

[Tim64]

Hey Guys,
Well, it looks like I'm going to go with a 700r4 transmission out of a 92' Chevy truck. I don't know the miles, but it's a good smooth shifting transmission. I'll get the transmission, drive shaft, torque converter, and cross member, which I may not be able to use. $250.00 for everything. Sounded like a good price to me. What do you guys think? Also he may have a flex plate, but he's not sure. I'm going to bolt this up to the 75' 250ci that's already in the truck. It has a 3 speed in it now. Can someone help me out with else I'll need. My understanding is the 700r4 will bolt right up to my 6cyl without any modifications, is that correct? I know I'll need some transmission lines. What else do I need? I'm not sure about the speedometer, or if I can use the same starter. I'm thinking I can't, but I'm not sure on that either. As you guys know this is my driver, and I can't have it tore down for very long, so I want to have all my ducks in a row before I start.
Thanks for the help,
Tim