In USA, the S12 uses 250 mm brake rotors. Same diameter as the S13 CA18DE turbo rotors, but considerably smaller than the S13 SR20 turbo rotors.

JDM S12 uses 4 different sizes of rotors. It doesn't really matter which size u choose as long as you get the entire strut/brake assembly.

1986 200SX Front Disc Brakes (with CA20E or CA18ET engine)
* 250mm diameter
* bolts to the back of the hub
* height 22 mm
* thickness 18 mm
* hub reg: 73 mm
Brake Pad: D274

You'll also need a sheer ring between the bottom of the strut and the knuckle arm. Any machinist can make this simple circular spacer, or if lowering you can use S12 RCAs.

As when changing any suspension parts, the car will need wheel alignment when it's finished

For the same size vented brakes, do the Silvia S13 Brakes swap -- no alignment needed, no sheer ring, keeps weight down for best performance

You can swap the entire strut into the 1200. Bolts right into the 1200 strut towers. To bolt it to the 1200 you need:
* 1976-1982 1200, 120Y or B310 (Datsun 210) LCAs, steering knuckles, ball joints

Bolt it in and see how high the car sits. Then adjust the lower spring seats to lower the car to where you want it. See Fastening Spring Seats

Use the S12 brake hoses to fit it into your 1200. You'll need 14" wheels (12" wheels won't fit over the large brakes)

Consider the S12 strut swap -- big brakes and relatively easy to find in the junkyard. Downsides: heavy (S13 brake swap onto 1200 struts is a better performance option). But some guys like the better strut inserts options for the larger 2" stuts when slamming the car into the weeds. You can use the Excel G inserts or Tokico inserts for 280ZX or any other common insert

S12: 1983-1988
* Nissan Silvia
* Nissan 200SX
* Nissan Gazelle