Ultimately, its all about reliable spark. These fellas seem to have a good working knowledge,
https://forums.lr4x4.com/topic/81300-are-ngk-bpr6es-really-the-correct-plugs/Interesting that the base plugs aren't as fussy about consistent higher voltage, as their dearer multi point\iridium tipped equivalents,
and all types seem to burn out similarly, especially if you're on a low mileage diet, which is probably 90% of Morgan owners.
Lower spec and more frequent replacement is probably the best\most economic way to go generally.
