Well that good idea, did not work well, as it was too tight in the area I proposed. Finished up making a little additional mod to mount a magnet, that required no drilling or changing the engine, except a hole in the timing chain cover. It worked perfectly, & I now have a reliable & steady sync pulse (1 pulse every 720 degrees of engine rotation). The little magnet mounting plate can be fitted in any one of 10 positions on the sprocket, so that a perfect spot can be assigned.
Just got to build a little fixed logic decoder, to get the timing pulses I need for the ECU, so the ECU only has to worry about all the engine sensor inputs & calculations.
P.S. The hole in the centre is for a crankcase ventilation inlet, so that filtered air takes a much longer scavenging path, through the engine.
You might have noticed that the Hall Effect sensor I used, has a little red LED built into the back of it, which makes it very quick & easy in real life, to ensure that the sensors are producing pulses. Should be good for trouble shooting.
Cheers Banjo