Maybe I missed this, but have you had a chance to take it out to check speed and thrust against the Bay's nasty chop and churn? You might be surprised if it has the proper prop on it? Shouldn't cost much to ask for a short ride? From the specs you quoted it might be able to do the job?
Started another more general thread about the boat, and the consensus among most owners of sister ships seemed to be the motor would be a little light, and that the 28 would have fit. Looking at a Alberg 35
If I decide to make an offer, it would be contingent on a sea trial and survey. Just trying to qualify it now. In addition to the boats lineage, the new motor was the strongest thing going for it, so sufficient power became the issue.
Now I'm wondering, what if conditions are benign during the sea trial? How do you really test for sufficient power? My biggest concern is not so much at sea (though that is certainly important), as handling in tight situations like a marina. For example, the boat might slide into her slip and stop on a dime on a windless day without current. However, how about with a 20 Knot tail wind. If the boat was bristol and slightly underpowered it would be one thing. However, I've got a lot of work to bring this old girl back to life, so it's important she's got the right motor, especially since it's new. Anyway, back on topic, seems the owner tried to save a grand and went with a light motor, as I suspected. How do I test it on a flat water day with no current/wind?