/6 rebuild advice

Just to clarify guys, the coolant has a layer of milky froth on top of it. The oil in the sump is perfect. . .

Checked the radiator tonight and the froth is gone/coolant color back to bright green......

I am going to do a compression / leak down test to rule out head gasket.

Fingers crossed....
I don't think you have a have gasket issue. Sounds like condensation to me, especially if it's gone now.