milling heads for comp ratio increase

I'll apologize if I have missed this, but I don't have a clear picture of what heads you actually have. Where are you getting the info that the heads are/were 60 cc's? If you are reading that off of a lot of sites, they spec out the NHRA minimums, not actual factory cc's.

The only stock 273 heads with nearly that small a chamber are those with closed chambers. But what I see here are the milling numbers you need for removing so many cc's from OPEN chamber heads.

And what pistons? Are they flat or do they have a mild dome on them? If we don't look into all of this, I fear you are waay off in your assessment of CR.

I see that you are going away from the milling idea. So much of this may be not useful to you anymore. But know that the 3% HP change versus 1 point in CR is quite misleading:
- That 3% number comes from a Wallace online calculator that makes oversimplying assumptions and looks at only one aspect of HP changes from CR, and so is not accurate to start with
- The number is ONLY for peak HP. It says nothing about HP and torque at lower RPM's. If you are road racing, rallying, or street cruising, then those lower RPM numbers are what are important, not the peak. BigBlock Mopar referred to this in post #38.

BTW, how are you using this vehicle?