Dave
If properly maintained, that engine will last for a few more thousand hours, possibly making it to 15k. A good survey will yield a lot as current state. Do not run it to destruction as these engines can be rebuilt providing another lifetime of service.
If one cares to a new coolant circulating pump would be wise as these keel cooled units require good flow given the length of piping runs. Presumably you have access to the maintenance logs, that will give a good indication as to prior care.
The hang ons like alternator, hydraulic pumps, hoses, fuel pump etc should all be suspect and have likely been replaced a time or two.
How about the genset and get home? Those too have similar needs and questions.
The 46, like most Ns, is one of the few vessels out there that spending money on an oldie is a "good boat investment" IMHO. Maybe a newer 46 with say 1/2 the hours is worth considering too to avoid the question you've posed.