It's easier to deal with a flat machined surface. The heads will have some variations in depth from chamber to chamber, along with your piston deck height variations. Why not have one side be a variable at worst.
Some of the really thin head gaskets don't play well with ede heads.
Edelbrock didn't do the SB mopar would any favors with those open chamber heads, IMO.
.060 depth + .030 gasket - ~.015 deck height = .075, so you need to mill the heads .035-.040ish to have it fit in a sloppy open chamber. Less piston protrusion = more milling. So you are getting close to a flat surface anyways.
Much easier to know your piston deck height and choose a gasket to make it work. Even the felpro 8553 perma-torques sometimes work well with the above deck 340 pistons.