Sumitomo makes a nice looking 175-50-13 that will fit (had them on my old street Spridget and have the 14" version on my MGB right now). There're a little too hard for my tastes, but a great value. They also sell a 70 series in the same width and diameter.
You can see them
~HERE~ .
The low-profile, 50 series Sumis look great. Due to the shorter sidewall, they will make your speedo read high (I just "recalibrated" my speedo with a GPS and small pieces of tape with the correct values).
If you want to have a real, pure look, Hoosier makes the A70-13 Steet TD. Pricey, but wold be very "correct" on this car.