Kaluk = Калюк in Ukrainian
Chances are the surname might not have been properly transliterated/sounds like???
Your Kaluk would be pronounced Калук??? This does not work etymologically.
Kaliuk/Kalyiuk is more accurate. In Ukrainian the surname is Калюк.
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Do you have any idea what is the name of GGrandfather's village or town?
What religion did he practice?
Keep in mind that technically from late 18th century to 1919 there
was no such geopolitical entity as Poland. The entire Kingdom of
Poland had been partitioned by 1775. Poland was reconstituted after
World War 1. The Galicia/Halyczyna Province, formerly under
Austro-Hungarian Empire, and Vohlyn, formerly part of the Russian
Empire, both a part of what is Ukraine today, came under Reconstituted
Poland's domain. After World War 2, these regions became a
part of SSR Ukraine. In 1991 Ukraine became independent.
If GGrandfather emigrated between 1919-1939, he was a Polish citizen,
but ethnically he was (by virtue of his surname) a Ruthenian/Ukrainian.
PS> There is a Ukrainian adage: because a kitten is born in a barn does not make it a cow.