I presume you are looking for a mechanical pump. You probably won't find one listed anywhere for a 240Z apart from MJP auto (Mr.F) or some of the US parts websites.
If basic electronics don't scare you, the clock is easy to fix. You simply replace the transistors, capacitors and resistors with new versions and she'll be better than new!!
Mmm, can't really remember the details Andrew. I have a vague recollection I just had to take the face off it - and the whole unit fitted inside the Datsun body. Some hot melt glue may have been involved.