I have a list of plugs that will work.
NGK B6HS & B5HS
Champion CJ7Y low profile ( I like these)
I've read somewhere???? there is a splitfire plug that works.
It's all about preference & reliability.
I gap my plugs within the factory suggested range (I have to look it up everytime I gap a plug :? )
nhman, I doubt this is what you wanted to hear....lol, but I choose reliability over hi-performance.
somebody here will have some input for you.