Milling the Heads How much?

Ok, so I have had my car in hibernation for close to 3 years, which has just about killed me. I have been starting the car and letting it run on a regular bases, last year I got the floors put in and was able to drive it temporarily. On a short trip the car started acting up and running poorly, lose of power, slight engine ping and generally not operating properly. So I limped the car home and discovered that the dizzy was toast, the shaft was worn badly and it decide that on my trip it was going to take a crap. So I managed to pick up a fairly new dizzy out of a wreck in the salvage yard. I got it all wired up and fired up the car and I now have a horrible miss at an idle, that even when you rev the engine it is still there. I double checked everything and it seems to be coming from number 5 cylinder. I can't drive the car, because the first/reverse rod also broke on the trip, and lucky I have one on its way. So my question is does it sound like a burned valve, still need to do a compression check. If it is a burned valved, which is an excuse to pull the heads. I want to mill the heads to bump up compression, how do I figure out how much to remove from the heads, how do you figure out how much to take from the intake side of the head, what about pushrod length. The block has about 50,000 miles on it so it does not need a rebuild, I just want to get a little more power out of the motor. I know I need to figure out how far the pistons sit down in the block and the cc of the combustion chamber, I have never done anything this complicated on a engine so I need help, and or advice. I want to thank all in advance

This what I have:
72 318 Block .30 over
79 Heads not sure of the casting number
1.88/1.60 valves
purple cam 276/284 .444/.453" 112
LD4B Edelbrock intake
650 Edelbrock carb
windage tray
double row timing chain
Mopar Electronic ignition with and orange ECU box
Dakota Manifolds

Thanks
Pete