Edelbrock heads questions!!!

Hey everyone, have a few questions(shocker right?). I have a set of edelbrock performer rpm heads and got them for a hell of a steal ($350 with the guideplates,bolt bushings and crane pro magnum roller rockers) They just came back from the machine shop from beign cleaned and checked so no there wasn't anything wrong with them! They are part# 6025 with 2.02 valves. My question is will they work with a stock 89 pistons without having the pistons cut for bigger valves. I am running a motorsport f303 cam.The guy i bought them off of said he was running them on his stock 90gt with no problems and i also bought the cam off him so he was using the cam as well, same exact setup that i am using, only diff was he was doing a carb setup and i'm doing efi. Is this true, can you use these with no problems? Edelbrock says that with these heads some motors MAY REQUIRE piston eyebrow modifications. I tried to check the clearance but didn't have clay so I tried to "improvise with something similiar" with lets just say less than stellar results. Anybody got any tips for that as well? Also edelbrock says that you have to use 5/16 hardened pushrods with these heads, do you REALLY have to use them? If so why? I thought the guy i bought these off of said he was using stock ones as well. Thanks guys for your time!