Rebuilt Ford Engine

1998 E 150 Cargo Econoline Van, at 142,000 main head gasket blew, engine froze up. I had a rebuilt Ford 4.2 liter engine installed, replaced the timing belt, egr valve, radiator & thermostat, altinator, egr valve, idle celonoid, plugs, pvc valve, air and gas filters, flushed the fuel system, water pump. Upon leaving and accelerating the engine pinged. I returned and told them it was pinging. They said it was the gas and try another station, which I did (several in fact). I returned and was told that there is too much compression in the engine. They rebuilt the cylinders, etc. And told me that it still had too high of a compression. It still pings upon accelerating and going up a hill. Is there any cure or am I going to be looking at replacing the engine again at 36,001 miles (warranty - 36,000 miles) The dealer tried to get Ford to install another engine which they refused stating that all rebuilt engines will ping. Hogwash - I am a female but I know better than that. Is there anything that can be done that has not been done?