The GPIO is driven with two, SN74AVC4T774 chips. 10k pulldown, 100 ohm series resistor. The 100 ohm resistor will limit your switching rate as you add capacitive loading, and you might have to worry about ground bounce, etc. with long cables. But this should give you enough to model it if you have concerns.
A fan-out buffer board could always be the fall-back position. I’d use something like a Max 10, so that you could get creative if you needed to drive all 60+ devices independently (e.g. one nibble is data, the other nibble is address for 64 independent outputs)
