HEADSET RIM SCREW HELICOIL SIZE ??

Hi - I am stripping a 1968 Italian SX150 for restoration and the long screws that secure the headlight rim to the headset bottom have sheared.
I wish to retain the original headset therefore will need to remove the broken screws from the lugs and repair the threads.
Does anybody know the correct helicoil size & pitch ?
Is it M3 x 0.5?
I wish to retain the original headset therefore will need to remove the broken screws from the lugs and repair the threads.
Does anybody know the correct helicoil size & pitch ?
Is it M3 x 0.5?