Mid 90's Mainships were more motor yachts than trawlers and took most of their design from Silverton (both companies were owned by Luhrs). I had a friend with a 362 Silverton (basically the same boat without the aft cabin. It was a good boat with lots of space inside. His had gas engines and it was a gas hog. Yanmars would be good on that boat. Make sure you have easy access to all the mechanicals. His silverton appeared to be bolted together with no concern for future maintenance.
John