he problem with the clock is the switching mechanism. If you change the clock source when the clock has just gone high, some registers may see a rising clock edge and trigger and some may not. This will cause your system to go into an unknown state which is bad. So I changed my switch mechanism to only change when the oscillator is low. I used the two free OR gates to gate my bistable LM555 inputs with the astable LM555 oscillator. I think my clock circuit is finished for now. I'll upload the full schematic as a PDF.