talked to owner of hydro dynamics but still need help with set up

[JEREMY243]

i just got of the phone with hydro dynamics the man in the flesh he will be building me a static plate (set back) for my 21' sob this boat is a challenger clone its a 1986 stallion 6.2 meter offshore built in orlando baught it off a guy on this site. the delema is that originally the boat was rigged with a 24" gil bracket with a late 80s 200 merc from the factory the problem is the 225 opti iam putting on is heavier which means it doesnt require that much set back . he suggested 12" but hes not totally familiar with these hulls . i need info on what is working for 21 supers or challengers so i can work from there. he told me he needed 2 measurements to achieve the proper angle. the distance from the top of the transom plate to the center of the top mounting holes of the bracket. the next measurement is aquired by putting a framing sqare to the back of the transom with the long side down and then measuring with the short end to the top mounting holes on the bracket where the motor meets . anyone following me. please answer if you have a super or challenger and give me your opinion .