Help with 1993 60hp rebuild

[Disco44]

Well just as the title says, I need to get my 60 hp back on the water and had some questions before I start the rebuild. The reason I'm having crack it open is the oil injection hose crapped out and now too cylinder has low compression on top of nice knock. The other 2 cylinders still have great compression and other than top cyl and knock motor runs great lol!
With that said is it possible to just fix top cylinder only or would that be stupid if I am that far in anyway? Does the head need to go to machine shop for resurfacing cylinder walls or can it be honed DIY?
Also the Mercury manual list different size pistons, how can I determine what size pistons I have? Is it listed on block or within serial number?

TIA for any help and feedback,

A.

 

[Faztbullet]

These blocks are bad about sleeves slipping for overheat/lugging of engine. You can fix a single cylinder if needed and sleeves need to been pinned so they cant slip. All pistons are standard size unless it has been repaired before. It will need to go to a shop and be bored and other cylinders "miked" to see if within wear limits.There is no head on this engine....

 

[Disco44]

Thanks fasztbullet, sorry for head remark I meant powerhead, but I guess if I'm going to tear into it I'll do all 3 and be done with it. I will get powerhead off and get to shop for boring size verification.