It took me 20 mins of stairing at you address decoding diagram to figure out what you were doing in it. I always thought of alocating addresses for I/O in terms of blocks of memory that needed to be access individually. When I first saw:

a13->cs1 of via1
a12->cs1 of via2

the first thing to come ...

I have been thinking on making my own portable 6502 based system.This is the basic layout for it.

Specs: RAM 32K,ROM 16K, I/O 1-4 W65C22S

Peripherals:
DIOS Ultra: PS/2 keyboard,LCD 40X4, RS-232 terminal, I2C EEPROM

Power:
AC: Old PC power supply
DC: RC car battery 9.6 Volts 1600 milliamp OR 4 ...