Need a Mopar guru: 273 part-throttle ping driving me crazy!

This won't be of any help, but about 30 years ago, I had a 68 Cuda with a 318 that had the exact same issue..and it drove me completely insane. I changed out carbs and distributors..intake manifolds...name it! Finally determined it must be a head gasket, changed them....and then the next week I changed out the heads as well because the gaskets didn't fix the problem. I flipped the car to a friend of mine who ended up dropping a 340 6bbl in it.
Granted, I was only 22 and didn't have near the knowledge and experience that I do today, but I often think back to that Cuda and the month of my life it consumed...and the fact that if BEAT ME!!!