In what your looking for is a displacement hull then your selection of engines is rather large. Yanmar, Cummins & Cat are the usual picks and as your not into the high RPM planing hull bit then it is about hours & maintenance RECORDS. If you jump to speed in a planing hull then it is CAT & Cummings 600 hp and below. Above that it is CAT or Mann.

Thing is you can in frame a Cummings or Yanmar for the same price that the parts will cost with CAT. I have always preferred CAT diesels primarily because I fished bill fish and those boats are made to run fast. Overseas I was amazed at the number of Yanmars in local fishing boats. They prefer endurance & economy over power & speed. My guess is you will end up with Cummins or CAT but you do see a lot of other makes around and for a displacement hull with low RPM propulsion many engines that are tried and proven are available.