I have tried whatever has been available!
Remember that either hydraulic or mechanical has no effect on the performance of the brakes, it's just an operating system, and hydraulic is usually more difficult to get right. First up is that the master and slave cylinders MUST be matched as a system, unless of course you are able to get all the maths right without experiment, and that's pretty specialised. So, if you are going to get some old motorcycle parts, get both the master and slave.
Then you have the leverage ratio on the pedal to the system.
Brakes for a CK often need to be different to a go kart type, wheel diameters are not the same, and according to a brake designer that is a huge factor, even with the same weight of vehicle, all relates to the torque applied by the wheel, so our wheels, overall diameter of around 25" are vastly different to a go kart where the overall diameter is about 10", and it's some sort of mathematical ratio, not just a factor of 2.5. I guess that's why motorcycle systems are a better solution?
The disc has to get rid of the heat, again all very well to get cool air to the disc, but unless the heated air can escape you gain nothing. Just like getting cool air to the engine.
More mass in the brake disc(rotor) will absorb more heat and radiate it more quickly so less fade, bigger pads = less fade, slots, cross drill etc also help dissipate heat, but not as well as more disc mass. More diameter helps too. Extra calipers on the disc is a negative help, as it simply shields the disc more.