LA318 Edelbrock Magnum v RHS LAX Heads

Any thoughts on the maximum/limits that can be typically/safely machined/milled from SBM 318 cylinder heads with a view to raising comp ratios???

Are there any particular SBM 318 cylinder heads "available" of "any type" that would be better suited to major/maximum machining/milling (as above) with a view to raising comp ratios???