These rotary pumps were prolific on Volkswagen and Audi cars and used for a long time, so parts should be available for them if there's a problem.
In order to identify the pump we need better pictures of the side where the flat surface should have identification info plus part numbers. That way we can identify who made it and what model it is. Ordinarily on Nissan engines the pumps were manufactured under license by Diesel Kiki, but if this pump is not original it may be just a Bosch VE rotary pump of unknown application. The throttle is on top where it is ordinarily for this type of engine.
You're saying that the engine won't run now or it hasn't run in a while?
EDIT: I just looked up '16700' all that I could read online and it is a Diesel Kiki injection pump, similar to
this one although not quite the same. The pump in the listing is for electronic injection. If we could get the last portion of the numbers from your pump we might be able to identify it better. It would seem to me that your pump is likely to be original to that engine.
As for priming that injection pump you will need to pull fuel through the injection pump by applying either a vacuum pump or an electric fuel pump to the return line on the pump and draw fuel into the pump from the source. Once you've done that you should be able to start the engine I would think. You will need to determine how the glow plugs operate on this engine since it looks to be a non-factory install? Also, the throttle cable is unhooked from the linkage for some reason and that would need to be reattached too at some point.
As for a manual primer if you could locate your fuel filter that may have a manual primer pump on it.
Steve