If you have a 52E or D/C that has been drilled and tapped you can purchase Davidson type bases from Sinclair International and have them fitted to the 52 by a smith. If your 52 is not d&t'd then the best I know of beyond drilling holes is the Viani mount, but it won't handle the Kelbly bases unfortunately.
You might consider doing what I had done. Use a Davidson rail and mount it to the rear barrel scope block holes. Cantilever the mount over the receiver and mount your Kelbly rings. Works well on my sleeved Remington 37. Both sets of rings are in front of the turrets.
Drilling 52 receivers is difficult, that stuff is hard as glass. bob finger