Hey guys, Just got a 1985 Mazda 626 LX (The 2.0L I4 Carb motor Auto)

I'm planning on working on changing the drum brakes to disc but don't know if I can retrofit any RX-7 parts or anything since there are no vehicle specific parts in the market anymore.
Also planning on working on the carburetor (stalls on cold idle, but doesn't have a manual choke), working on exhaust possibly, and seeing if there's any mods I can do or if it's better to ride it out until I can slap another engine in the bad boy.
The interior is also pristine with the exception of the center console being broken

I guess the main question is if you guys know what kind of disc brakes I can use on the car, If there's better instructions on tuning the carburetor, how to take off the air filter covers, if there's any performance parts, and
if there's anything crucial I can do to the car besides making sure my maintenance is perfect.

Thanks!