I am putting my A500 and ACA500 in there with one of Stephens adapters that extends the bus and adds a ZORRO II slot . My A500 already has a 2 MB Agnus chip, so this will be a pretty robust solution. I have not decided what I will do for a keyboard, yet. Maybe I should just add a RapidRoad USB to my ACA500 and use a USB keyboard and mouse with it.
You may want to check out the checkmate's bus board (on the checkmate's ordering sight) as it handle the a500 power, has a 86 pin passthrough and a Zorro II slot. There are also keyboard solutions with both a A500 and A2000 keyboard (also on the ordering sight).