Removed both cowl halves from the fuselage and joined them together on a bench using clecos in every other Skybolt hole.
Used a step drill to open up the #30 holes in the Skybolt locations that were not clecoed. I drilled from the inside so that I could determine if the drilled hole steps were concentric to the holes in the Skybolt flanges. If they appeared to be off I could apply a little pressure in one direction to shift the hole as required.
Once all of the non-clecoed holes were opened up the 15/32" I separated the cowl halves and installed Skybolt grommets and studs in each of the holes. I also riveted Skybolt receptacles to the corresponding flanges.
Re-joined the cowl halves and fastened them together using the Skybolts I just installed and then drilled the holes for the remaining Skybolts.
Separated the cowl halves again and installed Skybolt grommets, studs and receptacles.
Installed both cowl halves on the fuselage to check the fit. Looks good.