I was running my 421 Serval on 21cc Domes, 0.055" squish, a 1:1 ratio of 91 and 100ll, and using curve 3 on a Dynatek, which is 15* at 10-12K rpm (similar to +6). Elevation 1500ft. Didn't have any deto. I forget what my static compression was, though.
Currently running 91 octane on 24cc domes, 0.045" squish and 13* at 10-12K (similar to +4) I honestly haven't bothered checking comp on this setup.
These setups used Shearer SBIF and PWK 35s.
Hopefully this helps a little