1979 115 Evinrude 115999 some bubbles out of side of block runs briefly

[boatsRgreat]

Need advice- Put engine on muffs this year and started but didn't stay running. Thought it was fuel pump and rebuilt it. While watching it run seeing small bubbles out of startboard side of block along center seam. Is this a total tear down and just replace seals in block or could it be not that bad and be a stuck thermostat (s) or plugged water jackets? It runs choked with warmup lever but doesn't idle well.

Motor ran great last year, recent impeller, pees good, compression was good last checked one year ago. I am thinking of tearing into it or should I just repower and sell lower or get a reman power head?