Now that I've unwound myself =P I'm going to stick with plan A. Mill the head, with a sonic check to maximize it, and the valve guide seals if they can do it without a full valve job. If not, I'll ask for knurling or simply live with it.

If I can get to the 70cc mark it will get me to 8.4:1 compression and I can live with that, and continue towards building my good engine. If I happen to find a 4bbl high compression head for cheap, it's a simple head swap and my compression would go to somewhere between 9.2 and 9.8 depending on which year 4bbl. Decking the block would put the compression up much higher than I'd want.
Rebuilding an OHC Pontiac 250 with EFI and a Turbo