Spark Plug recommendation; blown 360

The correct spark plug for SBM Forced Induction is :

NGK 5671-9

But you might be able to get away with a
NGK BR8ES

Unfortunately, Bill Dedman is no longer with us. Do you see the "Legendary Member" status under his screen name? That means a member has passed away. He was a good old dude, too. He had just roughly finished a really cool 64 turbo Valiant build, too.