rodd, i believe the wide whitewalls were not largely seen on 113 cars, not even early ones. my guess is the whitewall on your datacard is a firestone phoenix with a thin whitewall. does it indicate tire type? my datacard does.
now about your softop. the chrome bar is literally nailed into the wooden bow, so it's possible to transfer it from one top to another. (i believe it's also still available from mercedes, incidentally.)
if your car wasn't ordered with a softop, it was likely added pretty shortly after it was delivered judging by the fact that your softop has the chrome bar. i don't think that particular softop was used very long (a year or two). it's a nice detail to have though, so congrats.