I'd be willing to bet that, if they were his creation, they were based off of the Japanese forms he learned and incorporated into his style. They're similar enough.
I'd also be interested to see if anyone knows more/differently, though.
I don't know if the any of the TSD versions of the Kichos are different from the SMK TKD versions I learned, but the ones presented in Kang Uk Lee's book are move-for-move identical. And the TSD/TKD Kicho Il Jang is move-for-move identical to the elementary Shotokan kata
taikyoku shodan, while Kicho Ee Jang is identical to
taikyoku nidan except that moves 6–8 in the Korean forms have rising blocks where the Shotokan forms have the same high punches that appear in the rest of the kata.
I have been pawing around various sources trying to get a handle on the history of the Taikyoku series—there were originally six—but unfortunately, the Über-source on Shotokan history, Harry Cook's
Shotokan: a Precise History, widely regarded as the best history of any karate style ever written, is... unavailable. I don't get this: it was privately printed in 2001, sold out almost immediately, and then... no more printings! Why doesn't he do another printing? I called Dragon Publishing, which distributed the book, and they told me that they have no idea if there will ever be any more copies... I'm really baffled: why write a book that everyone wants and then make it inaccessible to them? But that's the way it is, so we have to make to with the bits and pieces that are currently out there. What I've found so far is that the
Taikyoku series was used by Funakoshi as a `training' set to lead students up the the Pinan/Heian katas, but that he did
not invent them himself; they were apparently practiced in Okinawa for a long time before he came on the scene.
So unless HK's versions of the Kichos were profoundly different from what everyone is doing now, it seems to that, as JT says, he basically got them off the discount kata shelf and incorporated them into his own system. We need some input from the historically well-informed people over on the Karate forum... anyone out there?