The Walther P99 has mag release levers on both sides. If you get in the habit of pulling back the slide with the opposite hand in order to chamber from the open/locked postion, you will essentially have an ambidextrous pistol.
The H&K P7PSP has the mag release in the heel. The slide can be released just by squeezing the grip, so it is truely ambidextrous. I think the P7M8 version has bilateral mag release levers behind the trigger guard.
You can change the direction of the mag release on a number of pistols, thereby making them lefty-friendly as long as you chamber a round from open/locked with the opposite (the right, in your case) hand. If however you want to use a right-sided slide release lever, then the only one that comes immediately to mind is the CZ 85 Combat (there might be some H&K's with right side levers). It has safety and slide release levers on both sides. However, I don't think you can change the mag release button to the right side.