If you trust the step signals to be synched, you could do that. Also the may be other ways. I think the old darwin reprap printer had a belt engaging all 4 corners of the Z, maybe you can use something similar. Otherwise you can check stepper coil resistance, if its low enough like ~ohms then you can even tie 4 motor coils in series and get a total 4ohms which could be manageable. You could also use one paralleled step/dir/en and with just one of each you could drive 2-4 steppers drivers, e.g. same command for all.
I have a question just out of curiosity, what is original main uC on the Z corp printer, and at which Mhz it works?
I have a question just out of curiosity, what is original main uC on the Z corp printer, and at which Mhz it works?