That is how they go, the base of the rings sit ontop of those 2 ridges. Take that split washer out and that bolt will probably be long enough. The 2 allen screws then screw up to tension it.
There are 2 sizes in dovetail bars, short and long, 200mm and 330mm. Sounds like you have a long one. Ron at
sirius optics at springwood might have a short bar in stock. Give him a ring tomorrow. If he has one, take the scope and rings there to make sure it all works. Not sure what they cost.