Hmmm. The conversion ring is going to have some thickness, thereby moving the connection out by that much, but that may be accounted for in the electric motor
Is the saildrive already there or are you converting from a propeller
and shaft? If you are converting, all sorts of problems come to mind, because the thrust on a usual motor/shaft/propeller is taken by the engine
mounnts. You would need to get rid of it somewhere, either by hard mounting the saildrive to the hull
or by the motor
having a thrust bearing included and then mounting to the hull
Either way there are questions of weight and balance. Is the motor
weight similar to the Volvo
? Are you going to end up nose down?
Better tell us more about the design you have in mind. I don't want to respond with a bunch of stuff that it turns out is not relevant to your situation.