I had a friend check a reference book of Lithuanian surnames. The Lithuanian spelling would be KARC^AUSKAS. it is a common Lithuanian surname with the refence volume finding 184 examples in many townships across Lithuania.
The Polish spelling would be: Korczo(e)wski.
The C^ is pronounced as CH in English.
Best approach is to start with the most current US census from 1940 and find the ancestors you already know about and work your way back.