The only person designing accelerators at the moment is Jens Schoenfeld, and he's not interested in 68060s for various reasons... particularly because a new one would almost certainly lose him money and take years of his life. Interfacing a 68060 into an Amiga is far more difficult than a 68030.
If you need an acccelerator of that speed get one on eBay or Amibay- it'll be expensive but no more than a new one would be.
Back on topic....
Congrats to AmigaKit and Jens who I believe designed this rather ingenious piece of kit! Great for rejuvenating an A500!