There are two very small bushings for the shifter and Nissan should still sell them new from the dealer. If not, the junkyard will probably have them as they are the same from a 280ZX, B210, B310, etc. There is also a small nylon bushing that goes on the ball at the very end/tip of the shifter, these crack after a while too, and would give you more of an "all gears feel like neutral" feel than just the bushings. These are also available new from Nissan for cheap, or can be borrowed from the aforementioned cars, but they are a B*$ch to get off. My recommendation is to find a junkyard with a 79-83 280ZX and just take the whole shifter and bushings from it, it fits right into the 1200 tranny and will give you a shorter throw.

To replace the bushings, just remove the shifter handle by turning it counter clockwise, remove the rubber shifter boot, until you have access to where the shifter mounts to the tranny. If it's a stock tranny/shifter setup, there will be one metal pin going through the shifter with a C-clip on the opposite side of it. Remove the C-clip with a screw driver and DON'T let it fly away when it's coming off!!!! Then the pin will slide out or you can tap it out lightly, then the shifter just pulls right out. Basically reverse for installation, just make sure you seat the metal pin through the shifter properly or you won't be able to get the C-clip back on. You'll notice the pin looks like a round bolt with half the head shaved away, the shaved away part faces down towards the ground/tranny. Some models may have the metal pin threaded and with a bolt rather than the C-clip holding it on, it's no big deal, and really easy to do.

For the seats...I would also scrounge the junkyard for a nice set of replacemet seats. Stock Datsun seats leave a lot to be desired for in comfortability. I've found that earlier (1980's) Subaru seats bolt onto the Datsun 1200's seat rails with minor modifications (a little round file action to elongate the mounting holes). You just have to find the right color and best condition ones you can. I'm sure many others fit very easily too, just take a tape measure and maybe a set of Datsun seat rails with you to find the best candidates!

Hope you enjoy your 1200, they are awesome cars!

-Andy