The Targa part is from the Targa Florio...a 44 mile per lap and 900+ corners per lap race through the mountains of Sicily. Brian won the 1970 iteration along with the historic recreation..both in the wonderful little Porsche 908/3.
The Sixty Six may be a little bit harder to figure out.
Brian drove for the brilliant enginer/driver/team owner, Jim Hall in the Formula 5000 series.
Runner up (after missing 2 races while racing for Ferrari in Europe) in 1973 the # on the car was the iconic Chaparral Racing 66.
Brian then went onto win the F5000 championship for the following 3 years.