Since it is used for balancing, I assume it interface with some hardware. Getting the hardware to work and finding a compatible port could be difficult, unless its just serial or parallel ports
And you can stockpile those for not much money right now. And while they, too, will have correlated failures over the course of decades as they decay, at least it starts the clock back at 0 again.
You are aware that the C64 expansion port is actually the 6510-CPUs address and data-bus?
To properly emulate this cycle accurate in an emulator you'd have to attach about 30 I/O pins to your PC which you can update at a rate of 1MHz, with basically no latency between reads and writes, to connect external circuitry.