I trimmed the "U" channels that support the top cowl to length on both LH and RH sides then also trimmed the piano hinge for the access doors. I made sure both the piano hinge nested on top of the "U" channel nested between the firewall flange and the nose bowl flange.
After removing both parts from the plane, I laid out the rivet pattern on the "U" channel and drilled it with a #40 drill bit, then clamped the piano hinge into place and back drilled it. Then I clamped the piano hinge back on the top cowl and back drilled 4 holes which enabled me to cleco the "U" channel and hinge onto the top cowl.
When both sides were completed to this point, I removed the top cowl from the aircraft, securely clamped the "U" channel and hinge in place and back drilled all holes into the top cowling.
