Engine miss under load - ignition concerns

Well I think I have tracked down the engine miss. Installed new braided ground strap to chassis. No change to engine miss. Installed a buddies spare ECU (Chrome box) and running fantastic. I'll run it this way for a bit to make sure it is / has been resolve.

Do you think it wise to upgrade ignition system to something else? I have the MSD. Could convert to HEI? Thoughts?