[Ozzie Goat]

Thanks Gary.

I checked again, and the only method of ground is that the negative terminal on the battery is bolted to the roll bar in the trunk.
No ground straps at all. No grounding of block or heads.
The MSD grounds to the battery terminal.

I believe SpdBrake is right that my engine ground is dodgy and that could lead to arcing sparks !
Waiting on those new plugs.