Gear selector actuating arm , Lusso gearbox , Rally 200


I'm fitting a Lusso gearbox in my 1974 rally 200 but need to know which actuating arm I would need for the original Rally gear selector box to work with the Lusso gearbox. (Mine is missing)

When in 3rd gear position should it finish flush with the gasket face or 1.5mm? above (or is it below I'm not sure)

Is it the position of the arm that would make a difference or/and would i need to re position the 'round ish plate' (where cables fit into).

Any help appreciated