What year/make is the current motor and what's wrong with it? Only reason I ask is that you might be better off getting a rebuild depending on what you've got. That would come with a warranty and a used motor probably wouldn't.
Not a thing, yet. lol Its a 2001 225 Opti on a 2000 223 Champ. 350hrs, and honestly hasnt really ever left me hanging. I do maintenance every year and take dang good care of it, but I cant help but get knots in my stomach knowing it's 19 years old and bound to hang itself soon. I dont run it hard, mainly for this reason.