you can't cut more thread as the thread is rolled not cut. That means that the shaft with no thread is actually smaller diameter than the shaft with thread. I may have to just get some made up.

steering arms or tierods?

think 1200 ones are about the shortest, 180b ones are about the same i think
could always cut some thread off the ones you have so the can adjust in further

or just run an outer tierod end in place of the inner one as they are a fair bit shorter

im not sure of the ones that are on it do you know the size of standard steering arms?? and the 200b ones

25mm track? 12.5 mm per side. 6.25 mm per thread on each steering arm.

Will the stock ones will handle being wound in by that much?

I don't know any shorter ones from the top of my head. Doesn't mean they don't exist
I believe the Stanza ones are longer than the 1200 ones. But that doesn't help unless you are using 200B steering arms.

I've got a 1200 sedan with 200b struts in. I've moved the wheel track in 25mm now and need to change the steering arms to shorter ones. Does any one know if there are shorter steering arms available from any other datsuns or any where else????