Hi Tim,
Sorry it's not exactly what you're looking for, but if your RPA is the newer type and you haven't been able to find a genuine Kelly one, would an older RPA trigger be an ok compromise?
The dovetail was quite stripped and I then filed it out to make it fit a different trigger, but I found the correct one and no longer need it.
AI triggers also use dovetails if their factory option is more curved than your current one - available from Sporting Services.
It's free for you to have if you want to try it.