I run W18 Champion plugs. Supposedly the modern replacement Champion for the original 3X plug. You should be able to get them at any NAPA, but they may need to order them. Its been a while, they were around 6 bucks a piece when I got some.
"Could be the Jets"
- Dennis Wilson, Two Lane Blacktop
I noticed our A was running rich cuz I'd have to turn the choke mix adjustment all the way in. So tore into the carb, which had been rebuilt for my dad by somebody (I was 800 miles away). All the jet sizes were out of spec, mostly way rich. Swapped jets around and now it's fine, mixture wants to be 1 turn open to start, then close down to 1/4 open when warmed up.