I had to do the same exact on my 360. Speedmaster heads, and RPM air gap. Took off .030 thou and used the Edelbrock gasket. Bolted right up after that.
I don’t know how much was milled off the deck, but the H116cp pistons now stick out .003 above the deck.
Someone on here (or somewhere else) told me the Edelbrock is casted a little thick and most all needed to be cut. I don’t know how much merit that has…