Dear Paul and Hoyden. Paul. An Italian gold 20 lire of either Victor Emanuel II or Umberto I will be the nearest at around 21.5-22mm, can be purchased at little more than scrap in average condition, there is an Irish coin in gold that would fit, it is a gold pistole from the great rebellion of the 1640s but you would not get any change out of $100,000 and the chance of finding one is slim to say the least. Hoyden An Irish republic shilling of 1928-66 is 23.5mm, quite nice it has a harp one side and a bull the other, or alternatively a 19th century Italian 1 lire will also do the trick. All the best, Paul