Late to the party, looks like a lot of info to pour through in this thread.... but just want to offer that the mere thought of putting any money into an 8-1/4" is silly. And no, it won't stand up to ANY sort of real torque. Whatever website you saw that said it would stand up to 500 hp.... Don't go there anymore.
LemonWedge - Street heavy / Strip ready - 11.07 @ 120