Swapping Transmissions

[n3xb360]

i have a 71 gmc 2500 with a turbo 350 and a 2 piece driveshaft. i want to make it a manual instead of an automatic but dont want to give up my first born to do it if you know what i mean i found a super t 10 that i thought about swapping in, how difficult is it to do, do i need to shorten the driveshaft? do i need to change the cross member or the slip yoke? or any other transmissions that might be better? if you guys could help me out that would be awesome!

Merry Christmas to all of you