Perhaps it's the left hand that will be interchangeable for the exclusive? With the right arm bending at the elbow, I don't see how you can have an interchangeable right hand that would hold another item, like the gun for instance, and have it look natural. Perhaps you can switch out the whip with his gun in the left hand and switch out the idol with other items (sandbag, headpiece, etc.) to hold in his right hand.
Holding the gun waist high as the right arm is sculpted would work fine I think. Indy with the gun in his left hand would just look a bit odd me thinks as he is never seen holding it that way.