friends 318 build

Ok,a friend is getting ready to make some improvements on his '76 318 he already has the comp.477/.480 cam installed and will be using a Mopar m1 dual plane intake gasket matched to the 587 heads running 1.88/1.60 valves..my question is how much should he have the heads milled to raise the compression??...

Also what do you think he'll run..this 318 is in a '70 dart 904 w/full manual valvebody 8 3/4 with 3.91's he'll also be running a 600/650 carb and headers with 2 1/2 pipes..