no, once you do the plug chop, that plug is toast.
warm it up, ride to your long plug chop spot, put new plug in, ride thru all the gears and hold it wide open in 5th or 6th gear for at least 10 seconds, longer if you can, pull clutch, kill motor, once stopped put the old plug back in for the ride back
cut the threads off the plug chop plug to veiw the smoke ring, read the color..very light = lean, cardboard brown = good,
blackish = too rich
adjust main jet accordingly if needed.
i'd start with a 320 for that toomey and work down till perfect