boater8987- I think TRbenj was referring to what I was describing when he said "several inches below transom"
Regardless, some good info in this thread.
I'm not sure about the jack plates- don't really want to move the o/b back because the boat already sits low in the back if there is only one person in it. I think I will just look at O/B height with regards to the bottom of the transom, and if I have to just raise it vertically.
See pic, I guess this is a 20" shaft motor. Measured my transom and it is 15"
See other pic with red circle- I have always set the motor all the way down on the transom, just noticed this shoulder- is it meant to be set on the transom if you want to raise the motor?
I couldn't set the motor on the boat yesterday, but knowing the transom is 15" and looking at the motor with the tape measure, it looks like I may already be close.
Next step after setting transom height is to find a carb off a Johnson 15hp.... apparently the 9.9 and 15 of this vintage are exactly the same outboard except for the carb....