I also have Caithness Cormacks, but there are lots of them! Perhaps your uncles might have some names and approx. dates of ancestors?
Mine left about 1888-89 to Denver, Colorado, USA, then to other Western US states. My Cormack and the related families came from Wick, Pultenytown, Bower, Watten, Sarclet, Thurso, and Murkle, Stainland, some of which appear to be just districts now-a-days.
My main ancestor's names are Francis CORMACK and Dora WATERS. Dora's sister Mary also came to Colorado at some point-she died there in 1929.