I'll add my 2 cents worth NOT being a marine mechanic. I own 5 or 6 of these motors from 85-115hp. Very close to yours.In your initial post with the piston ring stuck in the head it would be very unlikely the cylinder wall is NOT scored. If it is scored then STOP.
Those motors are for sale all over the place for $200.
In the event you are going to fix it add roughly $100 for each piston and $100 for gaskets. Maybe more in Canada.
Now if it is 0.030" over, you have to match piston weight. If it has OMC pistons, then match them. If it has Wiseco or ProV then match them for weight.
Now in the event it is scored you will have to bore. There is not enough meat left. If there is, 0.020" is $50/hole and 0.040" is worth $100 plus $25/50 per hole for honing but you are already at 0.030" which puts you near the outer limit.
Now in the event you made it thus far, when the machine shop checks it for taper / roundness, those engines are all over the place out of round. When they bore it 0.010" it will not enough to make it round. I don't think they do 0.060" pistons but if they do then a kit is about $700 plus $5-600 in machine work.
You may drop a hone in the cylinder and it may look great. It might even run great. It won';t be round.
You may bore 1 cylinder over the others which is a No-No but it can be done if you match piston weight.
I would say 0.040" is the outer limit because the cylinder gets thin.
IMHO this is a learning experience, evaluate your budget first and how far you are willing to go.
Those motors are bullet proof yet very crude. But don't be surprised if the machine shop will not touch it or in the event they do you do not get results.
I had 130lbs out of distorted cylinders myself. But if it is scored, don't bother. Look for a running head and put rings/ gaskets into something worthwhile.
If you are like me then spend the money, learn and take the satisfaction in having repaired something. I have a 79/85hp being bored right now in 1 cylinder. It was stock 3.5" and it needs to go 3.540". I can only find pistons 0.030" which means moving over to Wiseco and doing all 4. Not worth it, buy and engine with blown gearcase and swap head out.
Not sure on yours but most rods are the same in the engine family/range/year. I bought a head for $50 unknowingly rebuilt 0.020" and was able to swap rods/ pistons to another motor after it was bored 0.020" You have to watch the bolt pattern though where it bolts to the exhaust / lower unit. I did see lots od O/S pistons on Ebay that are used as well but usually used pistons are just that however with the Chinese quality lately used pistons are equal or greater in quality. The issues I have are always in #3 or 4.
Good luck with your project.
