Agree with all the advice. As Kevin said, it takes two guide pins, not one and the shaft. It also takes the trans to be slung from above sometimes. Hanging on a chain so that X. Y and Z are all floating. A jack under can help that somewhat. A cherry picker thru one door will do the trick if all the parts are correct and installed properly. If you can get two long bolts started, they will be guide pins. (but not to carry load). Remove the two long bolts after two proper bolts are in.
The input shaft nose to pilot bearing I.D. is a pretty tight fit which needs a "straight in" install. The nose is on the end of a 125 lb cast iron chunk. It is about a 1/2 inch engagement.

Was this transmission mated to the engine previously?

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn