[The Fixer]

IMO, I wouldn't go down that path. A new rear isn't gonna help it drop 1.5 seconds in the quarter (unless he went from 2.14s to 3.73s or something LOL). Think of all the other things; what gears in the rear, what trans? If he did it old school, it probably has a Turbo 350 with 3.73s; not the best for highway cruising or any sort of gas mileage. It's something to consider when gas is over $2 a gallon. When he says it's 75% restored, what's left to do? You said it needs paint, so how is the body? If it's in primer, I'd be wary of who did the "work", and how it was done. It could be Bondo city beneath that spiffy primer. Between rust repair and a proper paintjob that could set you back $5000 easily, turning a car you owe $$ on into more of a money pit. And you might eventually have to drive it daily; snow, rain, etc? Your LS1 is a reliable ride, I'd stick with it unless you find a mint 1st gen that needs nothing.