Hypothetical 360 magnum build

Yes you could use those pistons in a magnum, not knowing exactly what they are I guess you would have to measure and weigh them. Magnum has a little shorter deck height, magnum pistons and pin are lighter by quite a bit. May have to juggle head gasket thickness to make it work.
Afew post here about the newer eq heads, not as good as the old ones but not much else for choices except for stock probably cracked ones.
Back to your piston question, if you ran this rotating assembly already, just use the same rods, pistons, balancer, flex plate. The cranks are all the same, la- magnum.