FWIW, I sell a new, super duty nodular iron 489 case with forged steel (counter-sunk allen bolt style) caps, and billet steel adjusters for $300.
You will spend more than that to put MW caps on a used case.
If I were going to run an 8 3/4 hard this is what I'd run. My 408 broke the 8 3/4 in my Dart on the second pass it hooked up. The transmission had to come out and apart along with rebuilding rear. I sold the rear end complete after I went through it and ordered a new S-60 from Strange.
Looking back I wish I'd been patient and found a deal on a used 9" aluminum center section and bought a new housing and axles.
