I have the stock backrest on mine, and it is the exact same as my brother-in-laws RKC backrest. You know that most of the backrests pads will bolt up to your backrest brackets?
Unless you bought your bike used and it had been changed the stock pad on the Heritage is about as wide as you would want it. I actually took mine off and went with a narrower one from a low rider for looks and to fit my T-Bag better.