Not so unusual it hasn't been seen before... you had a poor connection in the cap or coil wire to cap... there was an arc there that did all that damage.
Corrosion could have been a factor too. Don't worry about replacing anything that isn't burnt yet, but be critical of any carbon tracks on the coil as they are a sign that it arced too. Cap, rotor, wires for sure, maybe plugs, when running again spray with a mist of water around the coil... if it arcs you need one of those too.
The problem with a higher power than stock ignition is you are balancing spark intensity with spark duration. If it was running good with no ping, I would just replace the parts... If you make a change you may easily affect drivability.