Originally Posted by dabac

Well, for the least amount of style impact you can get a wheel with an internally geared hub and chuck it in there. I've even seen one wannabee SS rider do a stealth assembly and hide the shifter away up under the saddle....

Anything else and you're looking at a lengthy shopping list - unless you've got the old bits around and if they can be resurrected. If you haven't you're probably better off buying another bike, either as a donor or to use as it is.