To keep on the topic firstly, Congrats DATGRL, it is looking good. The SR20DE can really get a 1200 up and running with about 95-100kW at the wheels.

Hydraulic clutch is easy. If you don't run a booster. It's the booster that makes it all really hard.

Most clutch master cylinders are the same total length, but they vary on how much of the cylinder is inside the cabin. The 1200 requires that most of the cylinder to be out in the engine bay.

The other variable is the mounting bolt pattern. Look for one that has bolts "in-line" up and down with the cylinder bore.

Stick to the Nissan line of clutch masters, and you'll be close. Do some measurements of the brake master, measuring from mounting face, to the eye of the clevis pivot. The AE86/TA18 one like I've used in mine has more of the cylinder inside the cabin, allowing me to run a booster, but I had to remake the clutch pedal and part of the pedal box.

Cheers,
Chris.