Dont know your budget but if your lucky the heads may just need a valve job and new springs. If you have the $$ by all means get some new heads. I will embark on a 360 engine build in the future and I have decided I do not want to risk a flat tappet cam. Many have no problems but enough people across all MFGR spectrums have had bad experiences with the modern flat tappet stuff even though they followed every rule during break in. Converting to roller valve train on a mopar is approx $1100 plus. ($350 cam $350 lifters $100 pushrods $300 adj rocker arms.)
