are you running the 228mm clutch and flywheel set? single or dual mass? the dual mass entire setup from g260 e30 is = the g250 e36pn which is = stack height as s52's 240mm dual mass setup for ZF SG320
the S52 uses a dual mass setup stock, have you tried using that or at least comparing the original S52 clutch with the setup you are trying to run?
OEM sachs S52 clutch holds more than 350rwhp, so you could just run the stock item.
left is a E24 633CSi single mass flywheel setup in 240mm (OEM BMW)
right is UUC stage 2 single mass flywheel setup for S52 e36m with zf trans with Sachs e34m5 clutch+pp+friction disc
I would use whatever TOB is used in the E34M5 clutch kit
