You can slip the brass sleve that's in the stock BJ prop out and use it in the same manner. That's what ProBoat did to be able to use the larger props. I bought some K&S engineering brass tubing with the same ID and OD so that I can make adapters for all those props. The brass sleve in the stock prop takes some convincing to get out (it's not glued it, just a good fit), and fits in the Graupner CF props just as well. I also have used these adapters in GrimRacer and Octura props with perfect success. I'll measure the OD and ID of the tubing tonight and report back. You can buy the tubing at most Hobby Lobby craft centers or your LHS. I would guess that, if you bought the same size, aluminum and copper or SS would work well.