I think it's probably more of a collaboration, Rich Lasner (I think he was the then design guru at Ibanez) Mace Bailey (who did the woodworking) and Steve with his Performance customs all had a hand in it. All I'm gonna say is that Steve's white Sticker PErformance, has a near super shaprt identical lower horn to the JEM/RG shape, and that to me, is one of the single biggest differences between the Ibanez body style and the softer Soloist
body shape seen on most other super strats of the time.