not to sound stupid, but once you clearance the pushrod holes, lets say you go to a flat tappet cam after with the same heads- will you have excessive play of the pushrods now because the holes have been enlargened?
I can't speak for that but I can tell you, there is no going back to flat tappet cam in this motor (at least not for me anyway). If I ever sell the car I'll let that person know about it before hand.