I think the connection to the driveshaft may require some modification. I have a 67 Camaro rearend in my 'bird, and I think I had to fool with the yoke or u-joint during the install years ago.
johnny the firebird u-joint is bigger than the camaro. they make a u-joint that will adapt the camaro drive shaft to the firebird rear end or you could find a firebird driveshaft for the same trans you have and put it in. everything else will be the same, brake shoes, drums, wheel mounting, one thing to watch for is to make sure you have the same type of springs (ie) multi or mono leaf. you can install a mono leaf rearend on multi leaf springs with no problems. if you go the other way the rearend may be a little loose and move around.