The caliper that comes on the Shiv is designed specifically to be side pull so if you want to change to a center pull setup you will need to change the caliper. TRP make one that is basically identical to the one on the Shiv but is center pull. It, or something very like it, is what was specced on Transitions. If you get yourself a caliper off a Transition all you will need to do is get a hanger/cable stop. The Transition used one as a headset spacer/top cap and these can be bought aftermarket easily enough.
Just look at the front brake on a Transition and you will get what I am trying to describe.




Edit: added pic.