no other possibilites exist:-
bent valves, shot piston rings (althought that would be catastrophic failure and i think thats unlikely)

severe coking of the valves i guess (unlikely)

my fave would be a head gasket failure, and a pretty meaty one between the two cylinders, you might get evidence of oil/water loss/mixture /presurisation but then again depends exactly how the gasket failed.....

i guess a warped head is another pos (probably coupled with a shot gasket).

incorrectly adjusted valves (massively incorrectly adjusted...)

incorrect use of the compression tester (i know u used it right...but its still a poss) was there any idfference between dry and wet readings?



knowing the story behind the situation might help...did you snap a cam belt, were you running at high reves and suddenly it died, did you have an overheating incident etc,...