Iron Head Deck Surface Thickness

[burbfixer]

L29 454 heads.
What is the minimum deck surface thickness one can mill to? I already understand that manifold surfaces, pushrod length, valve clearance, and compression are affected. Stock they are .320" thick. It appears the intake seat will not be affected, so can they safely be milled .070 or .080 to gain compression without compromising strength too much?
Thoughts?

[pdq67]

Why do you want to cut them?

They are already down to like 100c 's stock.

pdq67