i dont agree. i'd put zero money into the old heads... get some eddie rpm's have a shop check all the clearances. go zoom. pep boys carries those heads. they have different models, i think the standard 340 model has 65cc chambers. but a machine shop could get it all set for you , flycutting pistons or whatever to get your comp ratio correct.
lose pounds + better flow = win
if you have real big dollars you can get mopar W series heads they have iron and aluminum but you are talkin' bucks there
no way in hell i'd spend a bunch of good dollars on 1.88 j heads. if you were building a factory original show car maybe