2005 40hp mercury low compression

[codemanz191]

i just got this 40hp mercury and it has low compression on the bottom cylinder.
here's my readings
cylinder 1 - 160
cylinder 2 - 150
cylinder 3 - 130
previous owner said oil pan gasket had a leak and engine ran dry on his way back to the dock, he said the engine was sputtering but he made it all the way in. he got the gasket replaced but guy working on it says it needs new powerhead.
i started the engine for about 5min before i checked compression, idled normal and no abnormal noises.
i personally don't think it needs a new powerhead. what would you guys recommend i check next, could it be just bad piston rings?
model number- 1A40412DD

 

[Faztbullet]

If it needs rings it needs rebuilt or a new powerhead

 

[codemanz191]

is it required to replace powerhead if rings are bad? also is there any easy way to check for bad rings?