Well theres a hot spot just waiting to develop detonation. Any damage from wayward rings or whatever will heat differently and retain heat causing pre ignition and......
Offset plug holes suck. The flame front doesnt burn correctly using the design of the head. Check a normal mx single plug head with decent perf and it will be in the middle of the dome so it can create an even burn so all power is created not lost.
I had. DG head on my odyssey. Went well and hePs of fun but that stiff axle makes them easy to flip but good for sidewYs stuff.
I would be drilling the crack and welding the plug holes then machining the combustion chamber and drill and tap a single plug hole. Odyssey engines get hot as the airflow is restricted behind the driver so im guessing the heat found the weak spot.