RWS DIANA MODEL 54 Weaver to Picatinny

Its a 30mm tube on the ATN (99% sure) so you would just need some extra high (high may work but Im not positive) 30mm dovetail rings. The other option is a UTG dovetail to picatinny adapter and use the picatinny rings included with the scope. I have the UTG adapters on a few guns and work pretty well.

That being said, I'm not 100% convinced that an ATN won't be vibrated/recoiled to death by a 54. Something like a Diana Bullseye mount may be needed to protect the electronics in that thing. 
 
Hope it has an excellent no questions asked Life time Warranty.

The model 54 is already known to be a scope killer.

It would be a shame to destroy a $1000 piece of instrument with out a good Life time Warranty.

This x2! The entire action moves on a sledge to reduce the recoil the shooter feels-the scope takes all the dual recoil and movement of the powerful action.