THe PO (Previous Owner) told me the bike developed a base gasket leak, and the Kawasaki dealership replaced the cylinder block with a used part.

Maybe the cam bearings were knocking due to oil starvation, 'cause the oil galley was stuffed with seals?

This is supposed to be round, like a doughnut...

...Not triangular and rolled over and up against the stud.

Another one. Three of the four seals were folded over and constricting the oil passage

How the fuck do you do this? Perhaps it needed pin #11 here:

I flew to Sacramento to buy what I thought was a good clean KZ1000J. Once I got there, the PO mentioned he had cracked the head by overtorquing the valve cover bolts, but it was ok, as he had JB welded it...

Note the crack in the JB weld (black arrow.) Also note the kewl heli-coil (red arrow). Tightening the bolt pulls the helicoil up, raising the oil seal like a curtain and letting the oil flow... over my trousers...

THe underside. The crack goes all the way through. The light area is where the paint has rubbed away from PO wiping the oil mess at every stoplight.

I guess PO didn't notice this crack on the intake side, there isn't JB weld all over it.