1973 340 issues.

sounds like a ring problem on #6 and a valve not seating on #2.....

Yes, my thoughts on #6.

Could #2 be a Head issue or is that not really likely? All along the Head Gasket I see what seems like oil residue between the block and the heads bubbling/popping away when running, but its not at #2, its from #4 to #6, maybe as far as #8.

Now here's a stupid question. :D When I do the Compressed Air Check tomorrow and I find its either the Inlet or exhaust Valve is there anyway 'dry' lapping that valve in place could potentially bring the valve back? I have heard of people lapping valves insitu with compound but I also hear that this can destroy the bore too.