I have a 14" RD artar in barel, a 14" APO artar in #4 Ilex, and a 180mm f4.5 in Barrel
The artar cells in the Ilex will not screw into the barrel of the 180mm Xenar or the barrel of the other Artar. Just a hair too big.
The artar cells in the barrel will fit the Ilex, but not the Xenar barrel. The thread pitch is different, so it starts but will not go past a full turn.
also, the artar barrel and ilex shutter give a cell spacing of 38mm while the Xenar is 34.85mm.
in conclusion id say that your artar will probably not fit a #2 shutter, but since neither the Artar or Compur#2 seem to have standard specs, there may be a chance. Your best bet is to measure the ilex barrel diameter and thickness with a digital caliper before you invest any money. I'm not sure how to measure thread pitch.