**Milling .030 off '920 - 273 heads**

Darwin what head gaskets are you using? you can get them in +/- .025 from the general .040's - that might help all on it's own. Or find the factory correct steel shim head gaskets, but good luck with that. Another problem is the bore size they don't make for a 273 anymore (that I have found) and the normal SBM gasket bore is around 4.100