Habbi said: snipAnyway I guess all I can do is keep using it
and keep a constant check on the oil level (which I should have been doing)
and hope the internals were not too corroded, pitted etc..

Habbi,

Wrong answer. You have options. Your best course of action, IMO, is to have
the gearcase inspected and any needed repairs done. If you continue to operate
the engine as is you are taking a big risk of untimely total failure. The cost
of a new gearcase may not only be much higher than a repair now, but the
inconvenience and danger of a failure at sea may be unacceptable.

My experience indicates that breakdowns only occur at the worst possible times
in the worst possible conditions. Of course, YMMD.

God luck, you sure will need it.

Butch