I'm pretty sure the Competition model comes with the right hand contoured grip, it was an initial selling point for me, along with the adjustable sights and the look of the slab side barrel. But Djg0770 it's definitely on the right track. A Ruger MKIII screams to be customized.
Check out http://www.rimfirecentral.com/forums/showthread.php?t=378734
I added a set of Herrett's Nationals grips with the adjustable heel rest, that takes a lot of weight off your wrist for shooting round after round, especially great when shooting bullseye style one handed. Many aftermarket grips like this can be ordered for left or right hand.
Modify the trigger, the sear, whatever floats your boat, but you'll love it more when you've made it yours.