yes as I told you before in a previous answer, with malossi and Scorpion you should get a short 4th. So the suggestion you have got was right.
the ignition 18 (yes it is PX125 setting) plug W3CC.
And for the carb set up, try what this guy suggested, as I told you I have never used this combination, though I still am afraid that with your set up the Scorpion is not a good match. Will work better a JL right or JL 2000 left.
But if you would have reed and higher tuned engine Scorpion will do it. To drive this exhaust your engine has to rev higher then allowed with rotary induction and a 24SI.
Let me know how it will go!