Right then, for a start off the 373 can more profitably be a 573 (MUCH easier to lay out)

I would put a proper reset generator on the thing too.

The 8 pull up resistors on the AD bus can be found in a single resistor pack - again easier to wire.

The max232 can be a MAX 202E (only needs 0.1uF capacitors)

And the CPU can be a Temic/Atmel or Philips 89C52RD2

You can even put the old Basic52 compiler in it, if you're feeling brave.

Steve