By fuses, do you mean white button circuit breakers?
As far as I know, there is very little documentation regarding the circuit breaker heads or the K200A series amps. I recently serviced a few circuit breaker heads and that's when I noticed that there was a version of the power amp that did not have the current limiter circuit included.
At the time that these heads were being designed, I imagine that there were a lot of production changes being made. I'm guessing that's also the reason that the circuit breaker heads didn't last that long and were soon replaced by the plexi front A-series heads with internal fusing.
The good news is that the basic power amp design is not much different from the later series amps, so the schematics will give you a good starting point for voltage value. I will look at my CB head and see if there is a pc board number on the power amp. Take a look at your amp and see if you can see one there.