Roller Block: Pushrods Rubbing Against Head

Did you measure for pushrod length? If not, custom pushrods may resolve the problem. "I" would look for any solution that does not require grinding or drilling at this point since your engine is already assembled. Not only that, but "usually" when you see this problem, there's always another reason for it than "just" the pushrod holes needing enlarging. I would look for another "more correct" way out. This of course, is only one man's opinion.