The worn section was filed away square and a similar piece of 3mm square prepared to fill the opening. This was left larger in length and cut away after brazing so I wasn't trying to fit a piece the size of a tablet. After brazing the excess was trimmed and filed away and as I had left the majority of the hole there, it just needed to be redrilled. I was lucky enough to find a pre-drilled trailer pin which I then cut the required slot in. I fitted 3 hacksaw blades side by side into the saw and cut the slot in one go. I gave 1mm clearance at the bottom to allow for a rocking movement to assist the arch the lever will travel through. The pin has been left deliberately long as I intend to wait until the shaft and clutch are in place before cutting to length and drilling for the pushrod and 5/32 ball bearing. Took a few hours in all but better than waiting weeks trying to find a replacement.
Finally had the gearbox dry assembled so I could measure up for the ball bearing holder. With the pieces in place I decided on the best length overall which ended up as 14mm overall. So the shaft was cut to that length. It looked too short but when I measured the 5/32 bearing it came it at just under 4mm so I would only need a hole depth of 3mm as I wanted the ball bearing to stand proud. Drilled the 4mm hole carefully after pilot drilling and checked the depth a few times with the ball bearing. When I was happy it stood proud 1mm I punched two divets to entrap the ball bearing. It can spin as it is supposed to but the divets stop it falling out. Handy if the clutch cable ever breaks. The repair looks good and the main bearing for the timing side is complete and in the post so I can start on that and maybe get to final assembly. Lot longer job than I ever imagined.