I ran a 1979 58' Yachtfish for about 4 years, it is a well built boat and would recommend one. They have a great range, are built really solid, and roomy. Every single 53' MY or 58' YF
built had only 1 generator. The one I ran had a newish 16kw Northern lights and it handled everything with ease and is what I would replace both with (a new one). The motors should go around 5,000 hours between overhauls if taken care of. I would recommend fixing the lower station as it is very useful on long trips and in rough seas the flybridge may be a little wet. You'd need 4 new cables for throttle and gears (although the runs aren't that long from the lower station to the engine rooms). As well as probably a lower helm pump. It sounds like the person did the least amount of maintanence they had to.
Definately get it surveyed, including hauling it and inspecting the bottom. I don't think you can go wrong with the price as long as the hull and running gear as well as engines are sound.