Unfortunately, due to the rather high display currents, adequate low pass filtering at output of 74LS541 is difficult. So, I would strongly recommend to avoid the routing of multiplexed currents along cables. Either you could move the multiplexing onto the display board, or you could use a static display. I would use six 74HC595 to directly drive the seven segment displays and would use a serial data transmission to them. You would only need three lines: Data, Clock and Storage. The whole transmission could be done in about 1msec.