Outboard disc spindle?

I recently bought a used pepper pot type outboard disc assembly. It has SPAQ stamped on it.
It has a counterbore in the brake calliper carrier plate to suggest an original type Lambretta disc spindle with the shoulder should be used?
Is that the case?
I've never used an out board disc before as I've always been to anal about originality!
It has a counterbore in the brake calliper carrier plate to suggest an original type Lambretta disc spindle with the shoulder should be used?
Is that the case?
I've never used an out board disc before as I've always been to anal about originality!