Saturday. I’m going for sure. Will likely be a crowd of us.

on the trim rings, they can be trimmed. In this pic you can see the tops trimmed to fit. Not sure how much room you do or don’t have but trimming may work.
https://cimg1.ibsrv.net/gimg/www.off...5507f8b3d0.png

my factory rings are trimmed, just dont think the stainless sealing rings would work because they are even larger than factory starboard rings. Going to reuse the original rings just routed out a 45 degree portion of the inner lip to accept more sealant

more important is to make sure the wood is sealed up. the factory was bad about not glassing up the holes. with all the vibration its hard to keep the exhaust holes sealed up with just caulk. a little fiberglass resin and a brush will make sure you dont end up with a wet transom.

The trim rings on my 35 are cut as well due to the high X. I resealed all of mine last year and did just as you have stated, chamfered all the edges to allow for a little more caulk then used a high end gasket making compound, Tightened up till I had a good squeeze out all around, let it set up for a couple days then did a final snug up. As mentioned make sure the cut outs are glassed up and dry.