Well, as I was unable to get a thumb in there to seal the plug hole up, I thought I'd throw the ol compression gauge on and see what I'm really dealing with.
#1: 70
#2: 0
#3: 87
#4: 112
#5: 100
#6: 0
.
So, it's worse than I thought. I guess Ive got some deciding to do - keep pouring money into this engine, or find a diesel to swap in.