While I have a CZC Bullseye, I have not attempted to holster it as the sport does not require a holster. I admit to considering carrying mine for "outlaw" IDPA as it is a reliable high-capacity SAO pistol that feels like a 1911. If I could find a decent holster for it, it would replace my 9x19 1911-pattern pistols for the sport.
A leather holster for the Shadow 2 might work, but I have two concerns: 1) The Bullseye does not have the extended dustcover of the Shadow 2, and 2) the thumb safeties of the Shadow 2 are low-profile. The CZC Bullseye has the extended thumb safeties which could get swept OFF in a Shadow 2 holster.