Russell--

I don't get what King Ashoka has to do with it. Sounds like a bunch of nonsense influenced by some reading. Seems doubtful that people in "India and other places" would be chatting about the Buddhist ruler from B.C. times and calling him a "wheel-rolling king". Especially as, I believe (?), the "wheel" he rolled was the Wheel of Dharma. Too esoteric. If anything, they'd call him Ashoka.

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The Hatfield-collected version has not come yet into this thread, so:

1946       Hatfield, James Taft. "Some Nineteenth Century Shanties." _Journal of American Folklore_ 59(232): 108-113.

In 1886, prior to July, Hatfield traveled from Pensacola to Nice on the bark AHKERA. The crew was, evidently, all Black men from Jamaica.

Here is their text for "South Australia," as presented by Hatfield.

CHO: Hooray! You're a lanky!
Heave away haul away! Hooray You're a lanky!
I'm bound for South Australia
SOLO: What makes you call me a ruler and king?
CHO: Heave away! Haul away!
SOLO: 'Cause I'm married to an Indian queen,
CHO: I'm bound for South Australia

"Lanky" would present another obscure reference. However, I think it's possible that "lanky" is part of a mondegreen.

You'Re a LaNKy = yrlnk
You RoLliN' King = yrlnk

The main consonants are the same. Which, perhaps, is correct, and which is mondegreen?

Quite likely that the phrase did not scan for Hatfield and he put out the best he could figure out. However, he did record "ruler and king" for a solo line, suggesting that perhaps that phrase was most accurate. And L.A. Smith did also record "ruler king" in her early (pre1888) version.