DonV....Thank you for the info & the links to prior posts. I'll have to read through he posts.

thank you again.

Here's how I'm planning on choosing bracket mounting height -

I have just taken some measurements from my stoner bracket (which has not been mounted yet) and FWIW, the bracket transom tops out at 4 inches above the platform (because the platform is set high compared to Hermco etc).

So, if top motor bolts are two inches from top of transom, that puts them 2 inches above the platform on my Stoner bracket.

I have a 300 Zuke with a 30 inch shaft still in the crate (So, obviously adjust for a 25 inch). It's a little awkward to pull a great measurement but it seems my anti-vent plate is 29 inches from the top motor mount hole, 27.5 from the middle of the middle hole. (I'm going bust the plastic to try and pull a better measurement to check this - if anybody else can check me, thanks!)

Bracket has 28 inch offset, which using 12-1 as the formula, would mean I'd raise the motor 2.5-3 inches if I want to round up a little extra.

So, to get the anti-vent plate 2.5-3 inches off the bottom of the transom, I should put the middle hole about 30-31 inches from the bottom of the transom to have some adjustment to play with.

Since the top of platform should hit 2 inches below the top hole, that would put the platform height for my 30 inch shaft motor at 28-29 inches.

It's worth noting Josh suggests 28-30 inches from bottom of transom for platform height for a 30 inch shaft - so I'm really just backing into his math.

Since almost EVERYBODY moves up a hole, not down, I will go with at least 29 inches for the platform - after double checking my measurement on the motor itself.