How much milled off heads to raise compression

My moparmates heads are 051 77-83 'hipo' with 100 thou. skimmed off!
Not sure which ones are Magnums, but they have little or NO chamber now!
Fitted with 2.02 vlaves and ran real nice without too much porting work.
I am gonna be doing a FULL-ON porting jobbie for him over the next few weeks.
Its a 318ci +30 rebore with ICON forged pistons and reworked 340 rods, being changed out for Eagles.
Beat my other moparmates 440 car with ease lol...

Just seen this a 360 bored +100 thou and destroked to 376ci and making 770hp...:wtf:


You would have thought they got the oilpan 'the right way around'...:thankyou:

2hp per cc 360.jpg