Thought I had to get rid of my 3 A500´s but if you are really gonna make that board then I shall surely keep them !!!
You mentionned a CF slot ? Guess you can dump that for the A600 version as it already has a pcmcia port and CF adapters are really cheap these days.
But one question, what about the Chip Ram

Most A500´s only have got 512 Mb Ram, A500+ has got 1 Mb Chip ... does your project include 2 Mb Chip like the A1200

:-?