i would never run metal shielded bearings on the clutch again, i did try it once on my eight and those thing didnt last 15 minutes,
just my 2 cents, run rubber shielded / steel balls bearings and you are good to go, also make sure you have a .3mm to .5mm play when you pull the clutch bell back and forth, metal exapnds with heat and stresses the bearings, better have a breathing space.
cheers
Ali