My stock LUK held the #11 plate in stock location (roughly 280hp... ). Slid foward about . 020, it would slip in fifth, and 4th with the trailer.
with the #100 plate, it would slip in lots of gears. as long as I didnt get on it below about 2100 rpm, it wasnt to bad, but it would only pull one gear. shifting would cause it to slip. I would *guess* that I was at about 330-340hp at that point..... so 280-300hp is prolly the limit for a stock clutch, and thats if you're nice to it.
FWIW,
we put together a 180 pumped truck recently. did 3KGSK's, 191 DV's, 370's, #0, no pump work, timing at 17*, and a B-1-2 and it only made 37x rwhp on the dyno at 5,000ft.
a 215 pump is the only pump I can see hitting mid-high 400's at the wheels with just bolt ons and a turbo (no internal pump work).
you're not implying flywheel hp are you??
--Jeff