The later trans will bolt up but you will likely have to use the side cover from your original trans to match your linkage. This will require using the 1-R shift fork from the later trans providing it has the same internal configuration.
Modifying a driveshaft is by no means cheap, and you have to find another rear end.
I would suggest putting an ad in the swap meet and finding a good original transmission. There are many people taking them out to modify their AD trucks to updated engine/transmission/differential conversions. I see them advertised all the time. I purchased one a couple of years ago for a 54 I was working on. It doesn't solve your low gear ratio issue but it would put the truck on the road.
Fred
Last edited by rfs56trk; 10/10/2017 4:37 PM.
