Let me add explanation why the holes were not symmetrical with my drawing.
There was a big engine starter handle as the red part shows.
It was impossible to make the holes symmetrical from the beginning.
Nice work Wayne, and a great shot of the seat and harness.
I can't figure out how the shoulder strap fastens though, and the lap strap appears to be a two pin buckle - not easy to unfasten in a hurry!
However, as there are two 'Clecos' still in the seat (at bottom right), it's probable that the photo was taken before restoration was completed, so maybe there's an extra clip or hook to be fitted to the shoulder strap?