The head came back, went back on, and life was produced. Joy and smiles aplenty.

In the process of trying to get it going smoothly we discoevered that cyls 3+4 were producing nothing in terms of power. Ctl 3 is not firing at all, and 4 is producing pops, but no power. Removing either/both plug leads for 3/4 does nothing to idle sound/speed.

New dizzy cap and rotor didn't solve anything. Swapping plugs and/or leads similar. Checked and adjusted vavle clearance (clearance probably larger than needed, rather than smaller)

Application of the compression tester produced:
1, 2, 3: 600kpa (or very close) == 85psi
4: 400kpa region == 56psi

Bearing in mind the engine was warm but certainly not 'normal running temp' (who wants to run up to temp on 2 cylinders?) I'm guessing I have problems down there. A good dose of oil in cyl 4 didn't achieve any noticable change.

I'm concerned that I may be jumping to the wrong conclusion though, since cyl 4 seems to be at least popping, but 3 nothing at all (not the other way round).

Thoughts?