Spark plug question for Archie

Archie, I'd be interested in what you think about using an automotive
harness and plugs for an O-360 with dual electronic ignition (EMAG/PMAG). I
read in Aircraft Spruce & Specialty that Klaus Savier (Light Speed
Engineering) recommends adapters to convert 18mm spark plug holes to 14mm
for use of automotive racing spark plugs to take better advantage of
electronic ignitions.

My A&P discourages use of non-aviation parts--specifically due to the risk
of too many "experimental" elements in an experimental airplane all at once.

Thanks.