I know your pain; see my Road Wanted post looking for a 27.0mm crown race for a Shimano HP-6400 (600 Ultegra) headset.
Unfortunately, I will be half a world away from my parts stash for more than a week more before arriving home. I do have a partial 105 headset from the 1050/1055 era, but can't remember if it still has the crown race or not. If your need is desperate, I could ask my wife to dig for it in my boxes, but I'm not sure that is a good idea for multiple reasons.
Alternatively, if I can find the 27.0mm crown race I am looking for, I could consider giving up the 26.4mm crown race from my NOS Ultegra headset.
Good luck with your search, and let me know if you think there's something we can do to help each other.