cam question

I have a 302 with older style heads on it and was wondering how big of a cam can i use and still use the factory rockers. what lift and duration, I want it to lope hard as possibe, thats music to my ears!!!!!!!!!!!!

Thanks for the help.

p.s. I have speed pro pistons flat tops with fly cut centers.

Comp XE268H for a hydraulic, flat-tappet. Keep lift under .480". New springs must be installed if you have the stock springs. Use the ones Comp recommends.

Jim