Given that a lot of the standard hops used for an American IPA tend to be on the citrusy side of flavors, I think just about any American IPA that uses cascade, centennial, citra, or amarillo hops would work well with some orange zest. I suppose the orange itself has the potential to be lost amid all the hops, but I think it could make the citrus flavor/aroma "pop". I did a great wheat beer with Amarillo hops and orange zest during the last 5 minutes of the boil and it was fantastic. For 5 gallons of an IPA, I'd go with something on the order of 1-2oz of freshly grated orange zest at the end of the boil. Good luck!