After looking at the stringers a bit more I am going to scratch the OB idea. There is a dealer near my house with these 4JH57 - YANMAR Marine...
Currently has a Gray Marine 625, I was thinking of replacing it with a 50hp. Just something light to cruse around with.
What I am considering may be blasphemy to some, but usability is more important to me than keeping her as she is. The boat is a 1953 cruiser...