Scale picture attached -a later PH5A where the role of the fixed and moving scales have been reversed - and marked for Mk7 ammo - check out the odd replacement scale screw - it happens!.

To fab a scale plate for your sight: the fixed "minute" scale would have used 5/100 of an inch graduations and five x 4/100 of an inch graduations on the missing siding scale to produce "vernier" increments of 1/100 of an inch. These should be easy to mark onto a fabricated plate with the right equipment The yard range scale zero is a little higher than the minute zero, so it is not a simple as swiping one line across for both scales - but it could be to get basic function....Even "spares or repairs" PH site lots are going for decent money these days...happy hunting!