I double checked the measurements for the holes and drilled from centre-top down both sides. I have already put the reinforcing glass strips under the aft edge, but there will be some minor hole mis-alignment after primer, paint and UHMW tape lifts the cowl slightly. I will be sure to make allowance for this as I open out the holes and position the Skybolt camlock receptacles.
Once the cowl was fixed in place, I checked the alignment of the air filter box duct with the fuel servo, checked overall clearances and ensured the alternate air duct closes automatically.