I broke down, pulled the engine and jerked the head off of it. Results???
Burnt intake/exhaust gasket, causing massive vacuum leak. Guessing a good portion of the air was being pulled into the engine from the failed gasket instead of the carb.
Pistons #3, #4 and especially #6 rock in their cylinders. #6 rocks roughly .040"-.050", #3 and #4 maybe half that much. Stupid tapping FOUND!
Combustion chamber for #4 is wet and possibly cracked. At the very least, a worn valve guide. (though I never noticed any blue or white smoke?)
A foreign object was introduced to #3 at some point in time. The piston, combustion chamber and intake valve are hammered to crap. Small piece of steel embedded in piston crown (chunk of compression ring?).
The piston rock indicates to me we have some egg-shaped cylinders, which means they'll need to be bored. New pistons/rings. Block and head decked. Valve guides (if the head isn't cracked). Valves. Prob cam, lifters, springs, pushrods, rockers. Gettin expensive quick, ain't it? And I haven't even pulled the oil pan off yet! LOL. Pics below.
Crap. Not where I wanted to be. Piston Combustion Chamber 
