Transom Bracket Mounting Height

[ApolloHT]

Hi Everyone,
As you are aware, I am am a Newbie to this forum...but I can't believe the experience you all have with transom brackets, so I will give you background.

I am in the process of converting my I/O to a transom bracket and OB setup. I unfortunately only have a 1" thick transom, so I will be adding (3) 3/4 sheets of plywood, with mat between, and mat, WR, mat, etc. over the last sheet. I then plan to use some angle braces mounted to the I/O motor mount pads, and glass everything in. This part of my project I have under control, and will utilize my creativity to (probably over-engineer it) build a transom to handle a Suzuki 250.

Now comes the bracket...which I have designed with a 36" setback...maybe a little extreme for tilting a Suzuki 250, but my family will enjoy the large swim platform I plan to build with the bracket.

My question: What distance from the bottom of the keel, do I mount my bracket? I have been told the rule of thumb is to raise the motor 1" for every foot of setback...therefore, for a 30" shaft Suzuki, I should have my bracket (or the motor mounting pad) mounted at 33" above the keel. Is this where you all start? I can always go up with the OB by mounting it in different holds, but to go down, I will have to cut my new bracket. How do you avoid this when initially installing an outboard bracket...what is the real "rule-of-thumb" for mounting a transom bracket. Any help would be appreciated.

Thanks,
John