20' seafari IO to O/B transom notch and outboard height

[samcfuller06]

Hi all, im looking for some guidance on cutting the notch in my 20' seafari transom. Boat had a straight 6 mercruiser and alpha one outdrive, both of which were fairly used up. I have a 135 Mercury Black Max that i want to put in their place. My question is, what are the standard notch dimensions on those of you currently running a notched transom ? Width of the notch Left to right, and how far up from the bottom of the vee, or down from the top of transom does the notch begin at ? I believe the merc has a 25" shaft. I'm going to verify that again in the morning, is there a rule of thumb with regard how high above the bottom of the vee the outboards cavitation plate should be ? Any help in making sure i set the outboard at the right height on the first go round would be very much appreciated, thanks in advance
Sam