How Much HP Can a 8 3/4 Handle?

With and auto i'd say yes...with a 4-speed i'd say your pushing it,my 8 3/4 has a "new" design 489 housing(more meat in the caps,and bearing sections),billet yoke,a moser spool w/4:30's,and moser axles..running behind my 416 stroker or 360 whichever is in the car,launching repeatedly at 2800-3000..the last thing i'm worried about if my driveline but if it does blow,you can bet a dana is going to replace it...:-D