Simple question here. I just picked up a very stock 72 chevelle for my daughter to drive around in. I have some spare parts left from my nova. My question is can I use roller rockers with pressed in studs or do they need to be screw in? I have a set of 1.5 ratio pro magnum with a eps performer intake that id like to throw on. Do I need to change the pushrods? Any help would be appreciated. Thanks