It looks a lot like the "Snowflake" as shown in the attached drawing from SAM 1066(UK), Dec. 1989 issue.
The drawing comes from an Italian source, and says it is the fastest model in the world by Bill Viets, at 231,406 km/h (143.82 mph)
Differences from the drawing are a cleaned-up tailcone, a more pointed spinner and a slighly different cowling. The engine indeed is a Dooling 61, and a 22,8 x 22,8 cm (9" x 9") "Super-Scru" prop is shown. Maybe the AMA has records of this world record, which could help confirm dates.
Hope it helps.