Creating a bush for this would not be hard but I doubt you'll find an off the shelf solution. You need to find some kind soul that can turn a bush that is a shrink fit into the pulley bore (i.e. goes in when the pulley is hot and bush freezer cold). The bush can then be bored/drilled out to the necessary size. BTW what are the sizes you need and what pulley? It may be that there are other ways to address the problem.