WHDload has quite a few options to make things work, where the easiest of them is to play with caches. The ACA1221 has a 68020 processor, which has only iCache, so all options are easy and quick to work through. When we're done testing the new ACA500 firmware, you can also play with CPU speeds.
On the ACA500, people sometimes forget that they don't have an AGA machine. AGA games cannot be played on OCS/ECS :-)