My 9.5 comp 340 with Ported J heads will knock on Winnipeg pump garbage...I don’t think you should jerk around with any of these half *** fixes, put pistons in it or run AV or race gas.
Lots of good info mentioned but if you hear pinging that is bad.... You can easily lift a ring land and other things. Take it apart and figure out what you have compression wise. It's best to stop now and save your parts (hopefully.)