dont think that oc95 is the right beast for the job...
i'll meet up with you this summer, and you can see the proper re-installation that i did for the yanmar 1gm10, and hear it run etc.
properly installed and mounted, the beta twin cylinder would be a much better choice. the only issue being that to mount the engine properly, it has to come pretty far forward and this usually involves relieving the boat a bit. the intention being that you really don't want to have (or should) to modify the engine's mount brackets, rather rebuild or modify the engine beds in the boat.
is eastern marine who quoted you on the engine? if youre looking for an installer they do beautiful work.
there is a guy on boatforsale.org who advertises yanmars avail in kingston. i might even considering buying a diesel in new york state and bringing it back if youre having a third party install the engine. or thinking of tackling it yourself.