FYI 741 and 742 are plenty strong for a light A body IMHO unless your planning on some serious dragging. 489 requires a crush sleeve or crush sleeve eliminator when you rebuild. 741, 742 do not. All 3 can use the same limited slip. Its interchangable between all 3.
Yeah only spirited drives here, plan on staying under that 500hp mark. I do plan on a sure grip no doubt, and did plan on 3.55 gears, but I guess I can see how quick it'll wind up on 3.23