mini sized 175/50x13 tyres not only look ridiculous on 1200s, but you'll be doing 4100rpm at 100km/h and 4500rpm at 110km/h!!! Screw that!
205/60 is a much better size and still available from Nankang, Sumitomo, Federal here in Aus. The Federal 595 is a very grippy tyre. You can fit them on the back of 1200s with the right wheels and a bit of liping and massaging. The front would take a bit more work, or just use a 175/70 if you want the same OD (again thery're still available)
If you must have a small tyre at least stick with 185/60 which is the same height as the stock 155SR12 radial so you at least keep the stock gearign which is low enough! They fit easily under 1200s. Again, they're still available in Aus from Achilles, Falken, Silverstone, Hankook, Nankang... no need to resort to mini tyres.