250/Tranny Combo?

Well guys I picked that 250 block up yesterday that I told you guy about. It's in great shape (pictures in a week or two) and looks like I will probably use it in the 48 for now. My question I have for you smart geezers is...
1.) What kind of tranny can bolt up to this?
2.) Would a 350 or 400 bolt up?

Later I would like to put in a 383 and keep the tranny without having to switch the motor and tranny two times.
3.) Also, since I have JUST the block, cam and oil pan, would it be cheaper to just build a 383 from scratch or try to find parts cheap on Ebay and CHR here and throw the 250 together for now?

Thanks for any help on this one. I am stuck in my plans for this thing. I have this 66 that I am doing and only thing on that I haven't decided yet is the color so I don't want to jump into two things at once. I am going to be taking it one at a time but wanted to post this question before I forgot and also to let you guys know I got the 250 now.

Shawn-