So they were ok for piston clearance? That’s my main concern about switching over.

Wondering if you found out of those j plugs worked for replacements? I run the buzhw-2 plugs in my 75 Merc 3 cyl and can’t find a replacement. I noticed in my manual that 90hp and up are BPz8h-n10 similar to the ones you quoted as replacement.
Hoping I can use them as there are tons available.