richp-I completely agree with you when you say you know what you're getting when you rebuild a 7.5 for the same price as a shot-in-the-dark 8.5. That's why I was originally tempted to rebuild my current rear, especially since my LS1 isn't going to be a beast; thanks for the rebuild run-down. However, you said the used 8.5 and a rebuilt 7.5 would be close to the same price. By the same token, for close to or less than that price, albeit with slightly more guess work, I'd have an 8.8. To me, it's a good compromise in the long run, especially if I win the lottery and decide to go crazy with HP upgrades. While I have no intentions of doing that right now, a 7.5 would nonetheless limit my options. Plus, it sounds like an interesting challenge.
jrm-Awesome info. I was talking to one of my Marines that's got a few fox bodies and a lightning and that was his recommendation as well. I will admit, his expertise with Fords is definitely a factor for me in this swap. I know he'll be able to help me out on sourcing and rebuilding a rear if necessary. I'll probably use the baseline kit for the control arms, since I'm upgrading the suspension anyways, so it's almost a sunk cost. Any idea when you're planning on doing the swap?