240K twin spot brake callipers fit right on. If you have the '79-'81 girlock brakes, at least. I've just done the conversion and put braided lines on and the car will almost stop on a dime. And that's with stock 200B rotors that to my knowledge have never been replaced.
Although rebuilt 200B callipers with fresh rotors and pads will be almost, if not just as good.
I'll second that, 200B brakes will be fine for a standard or mild L20B. Although if you do put some more power through it then the 240K brakes are definately worth it as well. I was quite impressed at how they performed on my 200B when they were the only working brakes. For rears, you can upgrade to Bluebird discs if you replace the entire diff assembly, but it's not really worth doing until you're making some more power.
A quick cheap upgrade is to fit 260Z drums on the rear. The
will fit fine on the standard 200B shoes, but they are lighter and cool down much faster.