I don't know, Bustyboi's seem like your just doing donuts and causing a noise-complaint in Futanari territory, the only real difference being semantics. What was traditionally just a chick you upgraded with a dick, is now a dude with a plump ass and big tits. I'm looking at images of the term on google and none of the better quality pieces have the characters look the slightest bit male. I'm pretty sure if you showed this to anyone who knows hentai, nearly all of them would call them a futa.

Also, it kind of just reminds me of that one American Dad episode, which honestly better visualizes the definition it's going for.