There are only two ways that cylinder would be at zero. One is a valve hanging open. If it sat long enough in the open position it could be rusty and stuck. The other is a broken piston or ring land. I am sure you would have noticed a broken piston. I had an engine with broken ring lands. It was a 1967 Firebird 400 HO. A high compression engine, but someone drove it on cheap gas and detonation cracked most of the ring lands. I only knew because I spun a rod bearing on a 1969 GTO 400, and I had to pirate a complete piston and rod from the '67 into the '69. Almost all the pistons were broken. So check those valves for proper adjustment and I bet that cylinder will came alive. In other news I found this video of a guy using an acetylene torch to repair an engine block.This is exactly what I was speaking of. Block repair