Re-fit the right cowling in place to see if I could see the drill holes for the mounting hinge. Positioned a light and I could see it. However, I think that I'll be able to reach in part of the way with the 12" drill bit to get the first few holes drilled and cleco'd.
Using a string, I also checked the center line placement. Looks good on the top - plenty of room to trim. Hard to get an accurate line with the string on the bottom side of the cowl however; will try and locate a laser level.