i have 327 double hump 461 casting heads on my 283 they are decked for one point of compression, 3 angle valve job, sodium core valves, edlebrock torquer intake (its an older style one) its also bored .30 over and i have a 327 crank in it. the cam has .525 lift and .230 duration @ .50. i am by no means a chevy guy but i had all the parts laying around and only had to pay for machine shop work and it turned out to be a bad*ss little motor. but the heads i have are pretty good for making power (or so i have been told) apparently there is a 461X casting that is supposed to be better than my 461 casting heads but im not sure, also im not too sure of the combustion chamber size on my heads either, im really bad with remembering numbers so i cant help you there but im sure someone around here know what size the chambers are. see if you can find a set of 461 heads around 461 will be the last 3 digits in the casting number (located under the valve cover) you might also want to go with a set of heads from GM performance they are supposed to be pretty decent and affordable