You might be able to modify the lower control arm to fit the 280 ball joint. I think the differance in length is the 280ZX control arm , which requires the crossmemeber to be modified slightly. The calipers need to be milled so they fit inside a 13" wheel but that isn't such a big deal.
Nissan Motorsports makes a coil over kit for the 1200 , do not know if it is still available. The adjustable ride height is neat to have but for a street car I never want to be bothered setting the corner wieghts every time I make a change. For the race car I have access to scales.
I'm using the H145 limted slip with a 4:11 gear , with my mildly tuned 85 HP wonder the lower gearing is no biggie. Also I did get the good racing valve springs so the motor will pull 8K no problem.
As for the A12 head on A15 not sure on that. For SCCA I have to run the A12 , Vintage doesn't care as long as it is an A-series but because I run VARA and SCCA I stick with A-12 block and head.
Basicly my car uses A12GX bottom end including GX cam , H-prod head with race valves and springs , weber 32/36 and header with 2" exhaust. Suspension is coil over 280ZX strut w/Tokico's in front , Koni adj rear shocks Nismo springs with track bars in rear. Addco 7/8 front bar and 5/8 rear. Over the last 15 or so years I've put maybe $4500 into it including the price of car.It is completely uncompetitive in everything except vintage and local Auto-x. The car always runs flawlessly.I insturct at track days and whenever I give a student a ride most are unispired by the complete lack of acceleration leaving the pitlane but after a couple laps they always remark what a fun little car it is. I've run some very fast cars including a 1000cc Yamaha powered single seater and by far I always have the most fun with the 1200. feel free to ask as many questions as you like. The guys on this page have an amazing amount of knowledge.

B210 glad to hear my street 1200 will become a reality.

Tom

PS I almost forgot Wilwood Dynalites are $130 a piece