Very neat! I'm sure your granddaughter will enjoy her train for years to come. I did a similar thing for a young friend of the family - and coincidentally, with a 591 Marx loco, although it is a windup. Every time he went back to "look" at the windup train layout, he would want to do more than look. I took a rusty 591 and stripped it down, then let him shoot it flat black with a rattle can (hard to mess up flat black). I put a late model riser gear windup motor in it for him. Now he can run it, crash it, he even wrote his name on the side of the boiler - it's his to use as he wishes. It worked out great; now when he comes over, he winds up his locomotive and we have train races! I should show him your pictures and see if he would like to repaint his train... hee, hee!