there are a number of ways to go about it depending on just how loose they are and the condition of the bore in the crank. assuming the bore isn't badly damaged and not too oversize you can do as John suggested and carefully dimple the outside of the bushing with a center punch to make it a tighter fit in the crank. either bearing or bushing should be set with red loctite making sure everything is completely clean before installation. IF they are very loose and IF the bore isn't damaged you might be able to use some shim stock to take up the clearance. shim stock is available in different thickness (.001" increments) and materials usually stainless or brass.