Having read through the thread since my last comment, I thought I'd post my hypothesis on a couple of things (I'm not hugely technically minded, so feel free to prove wrong, put straight, or tell to piss off )
1) Potential damage to block from snapped cam -: I'd imaging that most of the filings from the damaged cam will have been caught by the valve stem seals, so shouldn't have managed to make their way into the lower part of the engine. Though I accept that some of them could have gone down the gallerys into the sump, but to then have them picked up and spread round the engine by the oil pickup seems unlikely in my mind.
2) no compression on number 1 :- When a cam is tightened down, it has to be done in a sequence to make sure there is even pressure so it doesn't snap, so if a cam has snapped. Could it be feasible that the cam is now being held down over number 1 lower, as it snapped at number 6, therefore could it be holding the valve open slightly causing your low compression?