[Destroyer]

I don't know about anyone else, BUT I DO know tolerances etc. I know that the larger the hole, the greater the surface area and to me, the greater the surface area, the more likelyhood of water intrusion.

To my way of thinking the engine vibrates when it is running. No matter how smooth and quiet, no matter how great the anti-vibration system (if installed) it still vibrates. So if you have oversize holes that vibration is going to transfer from the engine, thru the bolts that the engine is hanging on and into the transom. If there is an oversized hole then the vibration must transfer thru the sealing medium first before entering the transom. So the larger the hole, the greater the chance of the vibrations, over time, destroying the sealing medium that it's passing through. It just doesn't sound like a good situation. Maybe it will last forever, maybe not.

Here's what I do. (Understand this is just my opinion, based on life experience and not some scientific answer)..... I take the holes that are there and I give them a very liberal coat of 3M 5200 sealant, inside and around the edges.. and I rub the stuff into the wood with a dowel, piece of scrap wood, whatever. Then I coat the underside of the bolt head and the shank of the bolt with the same sealant, slide the bolts through the holes, coat the area right around the bolts where they peek through the transom, touching the bolts with a continuous bead around the entire bolt, let it dry and then I hang the engine. This process insures that the bolt holes are 100% sealed against water intrusion.
If you feel that's not enough, then I would use some kind of epoxy liquid wood sealer https://www.jamestowndistributors.co...Fd5WDQodZ3oBfA that will be absorbed into the wood first, then after it dries do the process I described above.