Originally Posted by Crumb
If having a sandwitch is not a choice perhaps it could be possible to fit it in just one flat board... it would be slightly wider than the width of an A1200 accelerator but probably simpler and easier to build.
PS: original picture was done by Checker from a1k.org, my ugly red lines show an idea of how big would be the flat ACA500 :-) it probably could be made slightly shorter
Here is what I think some of the others where trying to communicate - please excuse my quick and dirty Paint drawings:
PS, the other option is just build a proper a500 expansion with 020 or better and plenty of ram.