Leupold 13 mm rings in Medium would fit well with your 452 American and your Leupold Rimfire scope.
The "3/8" dovetail on the 452 American in 22LR is very close to 13 mm wide at the top versus the standard 11 mm that can be found on most cz rimfire rifles.
I have tried a couple of different ring options on my 452 American in 22LR and the Leupold 13 mm rings in medium or Talleys (not the CZ 11mm version!!!) seem to fit the best. As I don't care for the look of the Talleys, I use the Leupold rings.
Other rings that I have tried like Warne or Burris will lean to one side on the CZ 3/8 (13 mm) dovetail. An easy way to see how badly your rings lean to one side is to mount the front ring onto the dovetail with the clamp to one side and then rotate the rear ring and mount it with the clamp in the opposite direction. Once you have both rings mounted, try to fit your scope or better, your ring lapping tool into the ring bottom halves.
Not even the Leupold 13 mm rings match perfectly but some rings that claim to fit 3/8 dovetail will show a mismatch of several mm between the front and rear ring when installed with clamps in the oposite direction.
K