I did this test cold, with the other spark plug removed and compression relief disabled... 110 psi and 125psi.
Is this right at the borderline of worrisome? From what I've read, these are decent #s, but a difference this size can be a bad sign.
The plug from the lower compression cylinder looks dark, wet, and dirty. The plug from the higher compression cylinder looks great.
I have a noticeable sheen following me in the water at idle, but have spark in both cylinders. Carb re-build scheduled next, then coils. I don't like this much oil in the water. When I disconnect the fuel line to burn what is left in the lines at the dock, the water discharge looks pretty awful, and white somethings are in the discharge.
The only real way to look at the cylinder walls is to remove the head. I would not do this due to the risk of breaking head bolts....a bigger headache...pardon the pun. It sounds like a carb rebuild is in order as you mentioned...they can easily gum up...especially if they have sat. Also, what are the condition of your fuel lines....today's gas with ethanol breaks down the rubber causing havok in some cases.
Start easy! New fuel. Do a spark test to check the quality of the spark... hot and blue jumping over a 1/4 inch gap.
My '57 Lark throws a lot of crud in the water which is pretty noticeable at idle speeds (little milky popping bubbles in the water?). Pretty normal for the old motors. You may want to do a Seafoam decarb - may even out the compression some and clean out some of the crud in the cylinders. If it's running and idling farly good, coils are probably ok. If you have good spark, leave them alone, and just clean/rebuild the carb.