A follow up
Today, I spoke with no fewer than 3 Designated Pilot Examiners. The 2 who knew what they were talking about (the other was pretty much seaplane only) told me the matrix is well spelled out in the Flight Instructor Practical Test Standards. Basically, any ONE of the former instructor rating check rides, IE, instructor Airplane, instrument, or MEI. The oral does not consist of the nightmare FSDO 6 hour hazing. Supposed to be very straight forward, parts 61,91, very little FOI and maybe a couple of commercial maneuvers. Citabria OK so long as the DPE is current it it. I really don't want to buy a set of Jepps to revise that I'll never use, plus don't want to rent a spam-can cesspool. So, off I go to find a 7ECA or something to rent. Probably find an experienced CFI to make sure I'm on the right track and go over the 8710, etc,.