I'd just like to add a tip to anyone having problems getting a Datsun 1000 starter motor which seem to be made out of unobtainium, after a lot of research on whether a 1200 starter would fit which was pretty confusing i took a gamble and bought one off ebay, even the seller said it didn't match up with my car but it looked right and the measurements we're right, anyway i just fitted it and it works fine, problem solved. 
   Pedro

This information is actually incorrect as i have just discovered that my engine is an A12/1200, bonus for me not so good for the theory of a 1200 starter fitting a 1000, it might be a good idea if a moderator deleted this post, sorry about that.       Pedro

Not sure if mine is an A12 box or an A10 i bought a wrecked 67 Datsun 1000 speedway car for the mechanicals to fit into my 1949 Ford Prefect as they are pretty well the same wheelbase, the Prefect had 10 BHP and the A12 has 69 BHP so it should go a whole lot better and with the Datsun suspension it should handle a lot better, thanks for the tips on the engine mods they'll come in handy when i need to do a rebuild. 

Prefects are cool Pedro, I used to have an Anglia 100e and 105e
first one with a kent and the 105e with a crossflow while a friend
was working on a longer wheelbase 100e with a windsor and some
mk1 escort forest rallye flares but sold it on sadly would have bought it
as it was almost finished just needed engineering and paint.
Dont understimate the kent or crossflow they are a fine engine.
As you probably know the L18 crankshaft is also used for the Kent
and Crossflow engines as an alternative for the expensive cosworth
full counterweighed stroker for a fraction of the cost and easy 1800cc
or a diesel crank and sleeved 86.5 bores for a super grunter.

Just getting back to the main subject, the first gearbox was from a 1000 behind a 1200 engine, then i changed to a 1200 gearbox with the 1200 flywheel and clutch now i'm running a 1500 engine with a 5 speed non dogleg box and a 1500 flywheel with the 1200 clutch plate , pressure plate, throw out bearing and clutch fork, all with the same 1200 starter motor, just shows how much these parts are interchangeable.