Iveco

I represented a boat powered with t/Iveco's. Our experience was very good . Parts and service distributor in N.J.
Run the engine numbers with them and confirm parts support.
About 8000 hours on the small 6's we sold years ago. Clean burning and durable.
You probably want to carry more spare parts then normal and keep your fedex account active.

I can't speak for assistance and parts availability in the US, but in the Med Iveco engines are quite common in commercial boats, where reliability is much more important than power to weight ratio, which often triggers the choice in most pleasure boats.
Which engine model exactly?
Considering the boat size and (at a guess) not exactly young age, they could be either V8 or inline 6, right?
If given a choice, I'd rather have the latter.