The Mainship 43- designation is pretty specific and refers to an aft cabin trawler built by Mainship in approximately 2000-2006. The last year it had 370 hp 6LY Yanmars and the earlier ones had 350 hp 3126 Cats.
Either will probably push that boat to a 15 kts fast cruising speed, but will burn a lot of fuel, probably 40 gph. Run it slow at 7-8 kts and it probably will burn about 5 gph for both engines.
Reviews and reports I have read from others were mostly positive about the boat, although I have no personal experience.
David