I hear you on the value of performance whether you can open it up or not. And frankly that hull probably takes a snotty day on Buzzards Bay as well as any thing
Pictures would be helpful but the thing you noted that struck me about the bracketed boat was the motor height. You mentioned it was mounted low on the bracket...
I think most bracket builders recommend 1" elevation per foot of setback. The SeaCraft hull seems to want a little more.
Assuming a 30" setback you'd be looking for the anti-cavitation plate to be 3-1/2" - 5" above the keel trimmed parallel to the keel. Also, do you know if the bracket was built for the Sceptre transom or a random add on.
If height and bracket angles are good, then a compression test is in order