Wow. It seems like to do what I really want to, which I think is read and write, I'm gonna need a lot more than I initially thought. Since the eeprom data pins are input and output, I will need a SIPO shift register to write data, and a PISO shifter to read it back into the arduino. I will also need a gate of some kind so that the shift registers in opposite directions don't screw each other up.
Since both A9 and OE pins require 5V or 0V or 12V in different circumstances, I suspect that I will want a more complicated chip to manage that independently. Guess I'll start over on my schematic and see where it goes.