Both my USP and USPc have compact ambi controls. The compact controls are slimmer and thus less obtrusive.
You will need either the ambi safety or the variant 2 safety (safety on the right for lefties).
You dont need a detent plate, just the safety lever.
You also need a 1/32 punch to install the ambi control loever. Swapping it out is not complicated, ive done several as i am a lefty, and ive done it for friends also.
HK calls the safety lever the control lever. Sorry i dont have any sources for the ambi parts except HK, e-gunparts.com has the lefty safeties
Instructions.
First remove the detent plate by pushing the pin holding it in flush with the frame, then the plate just lifts up and out.
Next using a punch the same size as the pin push it all the way out from left to right. With the pin removed pull the punch back just enough to clear the the far right plate (disconnecter) and remove the plate, this just lifts out.
Now just use another punch to push down the detent that is in the slot where the detent plate was. With it pressed down the control lever slides right out.
Part #24 is the pin holding everything down that you need to deal with
Part #23 is the disconnector
Part #26 is the detent plate
