I have a 65 country squire with a 66 390 that was originally a 2bbl motor,I am planning on towing a small travel trailer with it. Is there any later truck heads that will slightly lower the compression and have hardened seats. To get this motor to stop pinging I had to run a lower temp thermostat and richen the carb and run premium fuel. Due to the up and down prices of gas,I would like to be able to run regular or mid range fuel in this motor if possible. Jeff