I cannot give you any advice about the outboard requirements for this vessel and, given your history with the brand, I guess any testimonial would be akin to preaching to the choir. However, a friend of mine had an Outremer 40. It was superbly quick, shallow in draft and once, he went straight above a reef which I had to sail 18 miles around to end up in the same anchorage. The only criticism he had of the boat was its load carrying capacity on a long passage and tendency to bang a bit in a heavy sea. Still, this is a familiar mantra for those who sail cats generally. Good luck with finding a new power plant.
"if at first you don't succeed....Redefine success"!