I would start out doing the ignition as you described, do not go beyond 12:1a/f. Rich mixtures are hell on rings, ringlands, and make it difficult to read plugs. Start leaning out the engine to the mid to high 12s. When it feels sharp/ clean, start reading plugs for timing. Add 1 degree at a time. Use ngk plugs, watch the straps. Try to get your burn line ABOVE the bend on the strap if on pure pump, or on the bend with E10 blend.
Spend a bunch of money on several sets of plugs. Be diligent about plug reading. Much easier and cheaper to screw in plugs than change pistons.