turrbo, I would suggest looking for a local wrecking yard to begin your resto. I'm not as familiar with the ealier Z's like I am with the ZX's, but for seats, you might want to look at Honda Integra GSRs, Preludes, or other sporty cars as their seats are pretty good. Avoid the leather ones or else you'll end up sliding all over the place during corners. I think you can use your existing rails, you'll just have to drill them to fit the seats.
For rims, you will have a tough time since most manufacterers are making rims for the massive + offset that fwd cars have and not our rwd Z's. Try looking at old school rwd cars in the yard. Good luck.

82ZXT
71 510 autocross & 71 510 daily driver

 

There are few nice wheels from other Datsun Z's that you can use. Most are 14 inch and just a couple are 15 inch. The 280zx 1980-83 with T-tops comes with some nice 14 inch 6-star aluminum wheels that look nice.
But you can buy wheels spacers to fit newer FWD offset rims onto your car. Those will run you about $220 for a set of four, and then you'll need to figure in the cost of the wheels and tires...

 

I just picked up a haynes weber carb manual for 14 bucks, and it also covers SU carbs in it, just an FYI

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'73 240z
'99 neon R/T