Many years ago, I had a 1955 2nd series with a 283 that somebody had put a 2 speed power glide in it.
I found a nice 4-speed floor shifter and all of the pedals clutch etc.
Dropped the old 2 speed out no problem, but had the same problem as what you describe.
That last inch was a no-go. You do not mention as to what trans came out of your truck to start.
As Highflyer said, and everyone else, check your pilot bearing. The inside diameter of my 55 2nd was smaller than the diameter of my output shaft on the 4-speed.
It looked right, but oh no it was not.
Billyray,
I wish my shop manual was as descriptive as you are in mating a trans to an engine. Very well stated.
I could not agree more as with crenwelge, there is something about just stopping, cleaning up, put your tools back and calling it a day. Give your truck a overnight break. The next days has been some of my best wrench turning experiences.
Dale