It's a .47uF tantalum capacitor for decoupling but I doubt the value is critical.
You can't just parallel all the connections from the existing 6264, you also need to take the relevant chip select lines from the edge connector. There's also a write protect switch that ties /WE high if the switch is set to protect mode (and switches /WE through from the edge connector when not in protect mode)
I think I scribbled down a schematic at some point, send me a message with your email address and I'll try to find it and send over.