TheMontezuma on AtariAge asked me if I could design a small PCB that could sit where the Atari OS chip is located that contains an EPROM with 4 different OS versions on it and some jumper links to select the required OS.
Based on an idea by Igor Gramblička this is the provided schematic
Marcin was kind enough to take some photos of a freshly made board for me to share.
Discussion about the board can be found on AtariAge. You can get the boards/gerbers from OSHPark.