Hey dumb question have you tried settig your timing by ear? also have youchecked #3 and #7 sparkplug wires to make sure that there not crossed ? brother just had that problem 3 & 7 crossed. No back fires and not much noticeable problems other than a dog. Not trying to insult you but been there. please check the basics and dont believe your harmonic balancer/dampner even if it is knew. Good luck Tom.
P.S. Imost certainly could be wrong but that sounds more like a major timing isuue to me. I know that you checked the cam to crank timing. Its no the first time that Ihave watched one of your videos.
Just please check the basics to make sure that something else isnt wrong. Ive been there though Im not proud to say. but it more than makes up for it when the SOB runs like its supposed to