Turns out, he is the same guy who sold that SHA to Ricardo (Satan+) a year or two ago. He says that it is 100% M.U.S.C.L.E. It'll be interesting to see how high this one goes.
Attached is the pic he sent me last night. At second glance, I thought it was just a kinkeshi (I have a Bombe that is almost the same hue as a MUSCLE), but since this is the same guy that sold the SHA, I am sure it is the next Super Rare.