need help a couple small block ????'s

They'll work on the earlier block. (Comando as it or they are refured to now.)
All production Magnum heads are the same. Or so close to it you'll never know the difference.

What you'll need to do in order to have it work is;

AMC lifters. Though there probably listed the same as the small block Mopar lifters, be assured that the OE design is not the same. But they work. The thing here is the lifter must be able to surpply oil to and through the pushrod.

So, oil through pushrods are next. MoPar has them in there catolog. You may require a custom length other than what they offer.

AMC lifters, oil through pushrods of proper length and ends.

Oh, due note that the rockers are 1.6 and not 1.5 in there ratio.If theres an aftermarket cam in the block now, do some math and clearanceing of the valve gear.

.500 (cam lift) / (divided by) 1.5 (Comando ratio) = .33333333333333333333
.333 X 1.6 (Magnum ratio) = .533, the new lift.