We extend to you a cordial "WELCOME ABOARD !" Come on in, make yourself at home, we are a friendly group of enthusiasts, and we also appreciate the classic Chris Craft Roamer, Corsair, and Lancer boats too , as they are all on the same family tree and share much in common !
Okay, here is a nice 45' yacht. I believe she is powered by 8V71N's. A VERY solid engine that can go well beyond 5,000 hours if taken care of. In addition to an engine survey by a GOOD Detroit mechanic, here is the thing you got to look for when checking this one (or one like it) out. Ask the owner to do a cold start. A cold start is where the engine has sat at least 24 hours without being started and is bone cold to the touch. An 8V71N that is in excelent condition will start up on a half rotation with NO smoke. If it passes that test, that is about 80% of the engine survey as there is no way to fake that result.
If it starts and smokes a little, it could still be a good engine with alot of service left in it. I had a boat with 671N's in it, and that thing would take about 20 seconds of cranking until she fired up. Then it would belch out a huge ploom of white/grey smoke for another 20 seconds and then clear up and run clean. I ran the hell out of that boat for 6 years and she was still running strong when I sold her.
Remember, these engines were mated to Allison M20 gear boxes. They are famous for having the port side go bad. The later M20's, were built a little stronger to handle the power of the 6V92TA. It may not be an issue with an 8V71N because it does not put out as much power as the 8V71TI's that seemed to be too much for that transmission. Arcadian Marine in Louisiana can give you more information on that transmission.
Here is the link to what could be a very nice boat.