Hi Steve

Have you looked at changing the uP variant instead.In the 68pin package you have 48i/o pins.
Have a look at the ...

http://www.atmel-wm.com/products/...=T89C51RD2

High performance 8-bit microcontroller 64 Kbytes Flash
- 2 Kbytes EEPROM
- C51 CPU core with X2 function
- 64 Kbytes Flash
- 2 Kbytes EEPROM
- 1280 bytes RAM
- 40 MHz max Frequency
- 32 to 48 I/Os
- 3 16-bit timers
- 3 & 5 Volt supply versions
- Watchdog
- PCA input Capture output Compare
- 5 PWM