O.K. so i got a pair of pulse generators from a MC21 and left the bracket alone. Instead i shortened the pick up sensor to the correct length and double checked this had not altered the resistance, which it hadnt. So swapped the multi plugs over and earthed out the neutral wire. Wired up the coils and checked for spark.....yes....on one cylinder anyway. Swapped the CDIs and the spark swapped cylinders. Luckily i have a couple of spare CDIs so fitted one of them and bingo...two plugs sparking. So it seems that the MC21 pulse generators can be adapted to work with the bigger flywheel while leaving the brackets alone. Pulse generators only cost me £9 so worth a try as i couldnt get any for the MC16. So thanks for your advise Andy.