Used drilled aluminum ruler to drill #40 holes in hinge. Aligned with firewall hinge with forward end of cowling pined to the prop space with partial depth drywall scews. Easy to chip clearcoat with too much pressure from drywall screws. Marked inside of cowling at hinge rivet locations. Drilled and Cleco'd vertical hinges to cowling. Trimmed air and prop openings in top and bottom cowling pieces. Fit to firewall hinge.