Mounting of B-Bracket

[ReelToy]

I have a older bracket that I installed years ago on a old Albermale. It had B-Bracket decals on it before I had it powder coated I think it is a Armstrong. I want to use this on my 1986 23' CC SeaCraft with a Yamaha 250 OX-66 25"shaft. What I need to know is how to measure to mount the bracket. On my old boat I had it mounted 25" from keel this transom was straight. The transom on the SeaCraft is tilted out to top of transom. Do I raise the bracket to compensate for this? I know brackets have been dicussed alot and it's more than likely in the forum somewhere but I can't find it. Does anyone know a formula to figure this out.The boat is in the shop to rework and raise the transom.