BBC compression test results

I have an 86 454 that is stock aside from headers, and performer intake along with Holley 670 carb. The truck was given to me after sitting for 8 yrs. I was able to get it running with minimal effort, and for the most part has done pretty well. It was plagued with a rusty gas tank which caused me to park it for a couple weeks. Previously I had notices the occasional pop from the exhaust. As soon as the tank was replaced and fired it up it had what I thought was a miss. I traced it to cylinder one. The compression test came up with 60 psi on one with all others being 150. Any guess why it's so low?
 
bad valve or worn ring sealing or detonation damaged head gasket, or crack in head, are most likely issues in about that order
 
I am thinking burnt valve as it's not burning oil. No water in oil or vice versa. A friend suggested carbon build up so I am going to pull the header and use a bore scope to look in the port. What I am wondering is what could have caused a problem with just that cylinder?
 
I am thinking burnt valve as it's not burning oil. No water in oil or vice versa. A friend suggested carbon build up so I am going to pull the header and use a bore scope to look in the port. What I am wondering is what could have caused a problem with just that cylinder?
8 yrs setting up and moisture/ condensation. Metal attracts it even on the inside of the engine.
 
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