If the bolt holes are all the way through your job will be easy.
As far as bolts go, you need metric graded bolts, the stock bolts
are of good quality, unless the clutch has been replaced and the PO
used crappy bolts.
Check your torque wrench, those are like 8mm bolts and take like
25 ft lbs max, remember torque makes a steel bolt act like a rubber
band, and the stretch is what keeps things tight and in place. For
an application like a pressure plate, the bolt needs to have shear
strength, not really overly tight, just moderate torque will do.
What was the torque setting you were using? were you using a
3/8" drive wrench and converting inch pounds to foot pounds?
Wild