Which valve covers to go to

Bottom tap the holes
depending on the tap used stock installing studs can split the stands if the tap had a big taper and you screw in tight
you might want to drop a piece of lead shot or a bb into the hole before threading in the stud
with 25 lbs torque no way do you need grade 8 studs, they will not torque to stretch so you are using them just for the adjusters

Shims? whose "shims" are we talking about B3 spacers or flat shims that have to be bent? (not a good idea)