Here's the final numbers I ended up going with - this is based on the final confirmation by JR. I basically told them I wanted the "Omega Speedmaster Dark Side of the Moon 21mm CUZ003216" strap with orange stitching instead of black around the edges front & back.
@steelfish helped me confirm the sizing and I ended up comparing his dimensions, with my Omega Rally strap and then the dimensions of the DTOSM strap (from my Omega boutique). In the end, I matched the strap lengths with the stock DTOSM after trying the different measurements with cutouts.
21/18 widths
Curved lug
100/105 strap lengths
You have an Omega deployant
Black Cordura with black rubber around the pinholes; black stitching around the pinholes
Orange stitching around the perimeter of the strap - both on the upper Cordura and the lining