Hi Ed,
I'm trying to remember some of the happenings from the Nats 1983. About the picture showing the 2 Tiporares in Circus Circus colors, I'm positive that The Hipo-Tipo was flown by Danny Weitz. If you remember he work for Mr. Bennet. Do not know what engine he had in the Hipo-Tipo but on the regular Tiporare he use Webra 61. Also remember him working really hard to get the Dynamix carburetor to work properly. I do not know Danny's AMA number but the HT has a #81752, on the picture post #52. The Tipo next to it seems to be a Dick Hanson's Tipo with streamline longer nose. Your post #71 shows 2 different Tipos. The one hangins is a Hanson's Tipo, the other on the ground seems to the Great Planes Tipo, which has the shorter, wider nose.
Just my observations and hope that this may help.
Regards
Rene