Robert W. Gordon collected a brief version in California ca1923 that has "Heave away-ay, we'll roll and go!" Gordon says elsewhere that all of his seafaring informants had been to sea in the '60s and '70s.

So either "rolling/ ruling/ ruler king" were misinterpretations of "roll and go" (which seems unlikely to me), or else "rolling/ ruling/ ruler king" was as meaningless to at least some chanteymen as it to us, and they replaced it with a reasonable facsimile.