i'm using a recently rebuild 915 (5 speed, stock gearing....lots of fun with new power!!). I am using ....someone's stage 3 clutch, with .....i wanna say a powerhaus (2) flywheel.... could be out of left feild there...neither are stock, been a while... anyways, flywheel is light and lets the engine sing to redline, and the clutch grabs hard and never slips...kinda hard to do hill starts....
right now i am running 1 3/4" S.S. B&B's with heater boxes, the long collector version.
they are VERY nice, and are for sale....mostly because in my mid-year these headers don't allow for a proper muffler...not an issue with later cars.
-looking foward to following your build