Mopar Electronic Ignition Questions

I have read a lot of negative comments about the Mopar ignition converstion. My '69/340 came with this ignition installed, and it seems to work fine for me and I don't want to change it, but what spare parts do I need have for when/if it goes down?

Also how do I obtain replacement parts like the cap and rotor? Do I have to go to mopar, or can I go to the parts store and reference a particular model/year??

Thanks,