Sorry for the late-response time, I've been swimming upstream all week.
Indeed, the original Honolulu Blue was proprietary to WCF, and was Inmont "lab mixes", i.e. not off-the-shelf colors. I dug into one of my dad's files on the car, and lucked upon the original Ford documents covering the specifications of the original Ford build in 1968. The last page being the specs/instructions for Honolulu Blue. Not that it's going to get you anywhere today, but it's still a pretty nifty piece showing the lengths they went to for Mr. Ford's Mark II.
How exactly my dad and Jeff & Lloyd Brekke (they performed the most-recent restoration of the car) re-created the original Honolulu Blue is something they would have to recount, but my dad's in Colorado and I'm reluctant to trouble Jeff on a formula process that he worked-up 22 years ago. I know that it's Sikkens, and I know that the best that they could do as a benchmarking goal was to pay attention to the attached sheet and match to an enormous chunk of paint that had fallen off from the Desert Classics re-do in the mid-1970's. Yes, when dad purchased the car in 1982, the paint was literally "falling off" in large swaths in/around the a/c air intakes and quarter panels. So we kept some for future reference LOL. I have no idea where those might be today. All I know is that I've known the car since 1982, and Jeff Brekke really nailed the match and the pearlescence. It looks in my eyes precisely the same color it was when we obtained the car, just a heckuva lot slicker. Jeff is a frigging genius, at least in my eyes.
Well, that's all I can say on the color! Needless to say, I hope I'm never involved in any scrape-ups with the car in the future (knocking on wood) LOL. Honolulublueformula-1.jpg