The pilot lost directional control of the tail-wheel equipped biplane during takeoff from a 3,000-foot long, by 100-foot wide grass airstrip. The 2,500-hour private pilot reported that during the takeoff roll from Runway 35, the vintage airplane began to drift to the left side of the airstrip. The pilot added that he attempted to maintain directional control the airplane by applying full right rudder and aileron; however, the airplane continued to veer to the left and exiting the left side of the runway into soft terrain. The airplane nosed-over and came to rest in the inverted position. The pilot was able to egress the airplane with the assistance of a friend. The 79-year old pilot reported having accumulated approximately 1,000-hours in the same make and model airplane. Weather at the airport 7 minutes prior to the mishap was reported as winds from 085 degrees at 2 to 5 knots, visibility 10 miles with skies clear, temperature 29 degrees Celsius, dew point 15 degrees Celsius, and altimeter 30.10 inches of Mercury.