HooDoo,
I would suggest posting on Jan Still's Luger forum. Look for restorer username "Thor" or Tom Heller, username 'LugerDoc" for possible replacement part. I would think on a LRH Bolo the safety lever would have a partial serial number, so if it were mine I would look to have the button added to the original part by a professional restorer to loose as little value as possible, over replacing with a non matching part. I'm not sure how much difference it would make.
Regards,