Mfilos - that's correct I used the upper bit of a chicony keyboard.
I also tried a few mini-itx mainboards, they all should fit as long as there's a flat cpu vent. Also I'm considering putting a minimig inside.
How many keyboards did it take for you to look through, until you found one that exactly fit the width of the A500 case?
Looking forward to seeing what you decide to place inside of this rescued A500 case.
Also, amazing work on your restoration of the A500 keyboard. I have great admiration for people who have the patience to restore old things that have been neglected and it is clear that you take great pride in what you do.