Thank you everyone who chimed in. Gave me a lot to think about and made me realize I may have made a few mistakes and false assumptions when bolting the heads on, so I've decided to take a step back and verify some of the critical measurements before going any further with the rebuild.

One mistake was in a suggestion from a friend...who btw is a great mechanic & he meant well, but he's not much on the engineering side. He suggested the Fel Pro 0.037" composite gasket to reduce compression to run on pumped gas. I now realize this is most likely a bad choice at the sacrifice of quench, not knowing for sure if the heads were surfaced, and whether the CC's are equal across all chambers.

The plan is to remove the heads and cc all 8 chambers. A question I have is... once I know this, how close to each other should they be, and what is the best approach to equalizing them?

The second step is to measure the actual quench area across all 8 pistons (both ends and center of piston) to head using the rosin core solder method I've read a lot about. I believe once I know this, I can select the appropriate compressed head gasket thickness.
A few questions;
1) should I make the measurement without gaskets and the heads completely or lightly torqued?
2)Once I have this measurement, where in the 0.035"-0.040" quench area should I strive for...the 0.035" minimum or stay on the safer side of 0.040"? For instance, if I measure 0.018" quench without a head gasket, by using the compressed steel 0.020" gasket, I would be at 0.038" Considering the KB236 pistons, Eagle rods, average rod bearing clearance, and a rev limit of 6000-6500, this would be a good choice.