If your plugs are gas fouling, it doesn't matter which plugs you use, if even if your ignition is nuclear fission powered, it's still gonna foul them. Like Techinspector said, gotta get your carb and fuel pressure sorted out. I seriously doubt your timing is helping either. With that cam, you probably gonna want about 12° to 14° of initial timing. I'd definitely do that next, then bead blast or replace your plugs, and see what's up with the carb/fuel pressure.