What brand are the hubs??? If they are not u-bolt type and have the tapered hub, then all you need to do is get the correct inter hub. If they are Unverferth hubs all the outer castings are the same just painted different colors for different brands. So all you need on them is the different inter hubs and they will fit multiple brands.
I would not try to make a shim as it will just come loose and damage something.