As vindex1963 said, there is no substitute for a stock-pullied aluminum frame (Vision, cross bikes). It's 28mm wide by 154T. If you have an underdrive pulley, there are a couple of options: Polaris #3211168, which is an Indian belt, and Harley #40145-07, which is the belt for the international spec V-Rod. Both are 152T. The Indian belt is 24mm and the V-Rod belt is 1".
I haven't actually mounted one of these up, but I did the math and it should put the axle 3/8" - 1/2" forward from the stock location.