Well, I have a 68-72 12 bolt on the car....but to fit those tires, I have a pair of modified 15 x 7 steel wheels with 5" back spacing....the tires "just" fit. That is what is under the car, in the pix of my car next to this post.
Regarding using a 4L80, I know that its a little wider/taller that a T400, which we replaced with the 200-4R. So we did not even try.