Scott,
Thanks for the information and nice picture - your dad sounds like he was a real great modeler and very sorry to hear of his passing. I hope you are maintaining the family tradition
It's a long time ago but I do remember him saying that he had been taken for a flight by Bill Lumley in the full size Chipmunk when he was building his model. I thought it was one of the best models at that World Champs, beautifully built and very well flown. He eventually placed fourth but deserved to be higher.
I expect you have lots of photographs but here's another one anyway. Taken in England at the 1970 WCs with Maxy Hester (2nd) and Walt Moucha (5th)
Ray