Depends which engine you're using.
With the CA18, the amount the master cylinder sticks out is important. I like the AE86 sprinter (or TA18) clutch master cylinder. It's a good match to the slave cylinder on the CA18 gearbox. Also it's quite small, but the majority of the cylinder is inside the car, so I've had to modify the pedal box. If you could afford maybe 6 inches clearance in the engine bay, then a small spacer on the engine side, would fix this problem. The hole should be in line with the brake pedal hole. You could use a brake pedal off a 1200, and bend it so that it's spaced correctly. They bend easily in a bench vice.
The 180B one would also need a small spacer if you didnt want to modify the pedal box.
Sorry I'm not much help as to an easy method. But I'd be interested to hear what others recommend.

Chris.