Well, when I was racing, I found that the "G" series plugs, that is gold tip, worked very well, and did not foul. The plain plugs, I'd change twice a weekend, and the Gold, every other weekend. pLUS, A set I saved for a decade , when I put them in an old MGB that oiled the plugs up badly, ran fine on the old reced "G" Champions for over a year.
Does the body shop have a panel beater and an English wheel?