The pilot reported that he made his final approach to the 2,050-foot-long turf runway at an airspeed of 65 knots to compensate for gusty wind conditions. He would normally have flown the approach at 55 knots for a short field landing. As the pilot flared the airplane, it started to float down the runway as the gusty wind conditions dissipated when the airplane descended below the tree line. The pilot delayed making a decision to execute a go-around until the airplane was halfway down the runway. At this point, he did not believe the airplane would be able to clear obstacles at the end of the runway and elected to continue the landing. The airplane touched down about 800 feet from the end of the runway. The pilot applied the brakes; however, the wet grass runway surface reduced braking action, and the airplane overran the runway and encountered a ravine. The nose gear collapsed, and the firewall was wrinkled.