The primary adjustment is to swap a 6264 SRAM for the original 128 byte 6810 SRAM. This provides for 8k of space, and allows for more flexibility in that it will also accept a 62256, or with a trace cut and wire adjustment, a 6116. This also permits the replacement of the SRAM with an NVRAM.
I also added 5 additional switches to the address bus. This uses 5 gates on the 7417 open collector buffer chips, which were originally unused. With 12 address bits, 4k is available for programming.