this may not apply to utes, im not familiar with their rails.
ive had some nice 323 seats from an 86 mazda 2 door and never bothered doing anything with them. until today. to do this install, you will need some extra 12mm nuts (which can thread onto the mazda seat bolts). use locknuts if you can.

HowTo:
Simply, take the rails off the 323 seats, throw them away.
take the seats out of your datsun1200 (4 bolts 2 front 2 back) undo the rails (4 bolts again, this is a good time to silicon spray your rails) dispose of the 1200 seats.
get your 323 seat and bolt on the front 2 on the datsun rails to the front holes on the seat (if it doesnt line up drill out the hole and use a nut to fasten it to the rail). mark out a spot on the rear where you will drill through the 1200 rail, then through the seat. Drill those two holes, insert the mazda bolts and use the 12mm nuts to fasten it all together. Bolt the seats into your 1200 (ezy on the right rails) and wallah!

I was able to get the seat to retain all of its movements, even the front of the seat can be raised as well as the whole thing reclining and a lower back adjustment as well. wooo comfortable datsun at last, even for the lucky passenger