stealth heads on a 383?

Sounds like your adjusting everything to fit rather than getting the parts that fit and in the long run, work better together without tweaking it to suite. I like the iron head plan and the KB piston option with a slightly thicker gasket for pump freindly gas ratio.
Pushing the issue with a iron headed pump freindly ratio leeds to problems later. As carbon builds up and change of season feul blends come into play, detionation can be an issue.
The difference in 1pt. of ratio is small peanuts in the overall output.