I also don't think Wilt is an outright liar like some people do, I think he's more of just an entertaining "story teller" in the sense that he embellishes things to get a point across - it just sounds ridiculous to people that don't understand this because he's embellishing things that are already impressive or otherworldly enough that they wouldn't need any exaggeration. If he's referring to the foul circle - he's likely embellishing his ability to free throw dunk. But has anyone considered that he might be referring to staying within the half-court circle? His 3 strides might have stretched him out that far, just a thought.
I'm too not sure that I'd endorse Wilt's character with regard to honesty. And I haven't read through the whole thread, but in "Wilt: Just another ..." his first book (his autobigography, written at the end of his career, rather than his later books which were more opinion/musing based and which included claims of 50" vertical and 20,000 women) he claims to have run up from around center court (could dig up the quote if anyone really cares) for his free throw dunks. No mention of 3 steps (which I don't personally believe, but Wilt did have very long lengs so would cover greater disances in fewer strides). I tend to doubt 3 strides and don't know whether or not he was breaking the plane of the ft line (as I vaguely seem to recall Dr J doing for his free throw line dunk), to me it's not really that relevant. Wilt was a tremendous athlete and anyone who thinks he was only good because he was playing in an predominantly white league doesn't know their history.