First question is what is the make, model and size of the yacht??
Second question has to be what is the budget.
Most new marine or marinised diesels around that horsepower with gear box seem to cost between $8k to $11k.
First option is to rebuild the 2 QM but you won't know how far you have to go until you get it out and strip it. If you can get away with honing the liners, rings, bearings, seals, gaskets, head recon and injectors and pump recon, it might be worth it. Say $3k to $4k.
If you do that you know the engine is going to fit back in the boat without engine bay modifications.
If you are going new, I would be looking at a 3 cyl engine with heat exchanger as a start. Re brands I think it is hard to go wrong with a Yanmar or a Beta Marine marinised Kubota.
Diecon Marine marinize second hand imported Kubotas and put a gear box on them and a warranty.
I got a quote from them two years ago at $7,555 + GST + freight for a second hand Japanese import with gearbox and control panel or $1,000 less if you supply gearbox.
They do new engines as well and the equivalent quote for that was $9,800 + GST + freight. I think I would pay the extra $2,300.
COR Cooling - Diecon 1800674110
Beta Diesel - (02) 95251878
www.betadiesel.com.au/
