Early Corvette rear vs. later model

[J68Bird]

OK, since you guys got me into this, I need you to help me out on this one. When I started this project, a 68 Firebird Conv. all I wanted was a nice car. Then I started reading all the posts on Pro-Touring and decided that I needed alot more stuff. It started with the big Corvette brakes up front. Then came a mini tub. Then I figured that since I have to cut the frame rails (in questionable condition anyway) I might as well replace them with 2X3 pre-bent rails. Since I'm moving the rails, why not go ahead and put the full Corvette IRS in there. While mentioning to my neighbor that I'll be putting in a Corvette rear he say's that he's got one I can have. Problem is, it's from a '68. So my question is, should I use this rear or sell it and get a later model unit? What are the pro's & con's? I have to add that I'm doing all the work myself and having a blast, but each change in plans ends up costing more and pushing back the completion date.

J. Clear