My builder has the ACT twin (forget the exact disc pairing since they offer a lot of options) in his 875 RWHP corrected (it was doing a c-hair over 900 uncorrected, which is what the clutch is actually dealing with) C6Z. He also has a customer he built a LSX 454 w/ a YSi that is well over 900 on the ACT.
Anyway, FWIW I haven’t heard the horror stories from the SPEC Twin that the singles have.
So what broke? Sorry to hear something let go… good luck getting it fixed!
-TJ