Timing is critical on them, on a similar setup I never did figure out exactly what the timing was but kept jacking it around until it was just right. You have got to let the engine tell you what it wants, do not get a specific number stamped into your head that will lead you down a false path. Remember you have changed how the engine runs and you must let it tell you what it wants.
before you do it you have to have all else perfect, new plugs, wires, coil, carbs etc - it has to be perfect or you will use the timing change to cover another problem (I do this professionally and see this often) and things spiral downhill from there.
I don't know where you are but weather will affect things as well, I do the supertune in warm weather. If I tune an engine in Feburary then it'll run good in Feb and will need to be redone in August.
