27 bit parallel Bus @65MHz: Use 3.3V or 1.8V?
As all things are equal in your description (ICs available and operate  in both voltages), the 1.8 V solution will be the better choice. Your reasons listed are correct and signal rise/fall times should be better and will be no worse.

The 65 MHz signals should not be corrupted on their 80 mm trip to your PCB if you use a good, standard cabling/grounding scheme (outline more in your question and I can expand this answer).