I could approximate the thrust by knowing the weight of my aircraft and timing the acceleration to takeoff speed, but I think that would be a little dangerous of me as well as only an approximation due to rolling and wind resistance as well as inaccuracies of the airspeed indicator. I also realize the thrust would vary as airspeed increases due to changes in propeller and engine efficiency.
Nevertheless, was there every an actual rated or measured thrust for the C172? You can use whatever year model you want, although I usually fly the C172N at 160Hp using a stock propeller. I would also assume if there was a measurement, it would be at standard atmospheric conditions (sea level, 15C, standard 29.92 pressure).