Hi jacking here but still asking questions along this line. I was wondering myself as well and was also wondering about the aftermarket aluminum offerings as far as the difference between one seating special offset rockers and ones that could you just use Factory rockers?..
Jpar, about the only heads that need the hi buck offset rockers are the victors, speedmaster Victor copies, indy 440-1, and B-1s ( and badder yet race heads)
From trickflows on down, (stealth,, promaxx, rpm) stock or non-offset rockers will work, depending on camshaft.
Still, if your buying something, I'd make sure about the rockers first.
(I've got a pair of victors, if I don't use speedmaster garbage, the rockers will cost more than the heads....)