VERY VERY interesting. I like the 2 address bits that are used only on the IIcx/IIci, that's fascinating. Interestingly, Pins 4 and 5 (A0 & A1) correspond with the A0 and A1 of the onboard ROM of my IIci, so i'm not exactly sure what this means. Also the alternate chip select (Pin 63) is interesting.

From what I can tell on my IIci:

ROM SIMM Pin 63 = +5V (not selectable)

ROM SIMM Pin 2 = Pin 21 on 68030 & Pin 25 on NuBus controller, C7 in Cache slot

ROM SIMM Pin 3 = Pin 22 on 68030 & Pin 20 on NuBus controller, B7 in Cache slot