Continued with marking the top cowl for the firewall flange and side split marks. Placed 1.5" tape on the firewall flange, and use the 1.5" width to mark the aft portion of the top cowl. Marked the left and right split lines on the aft portion of the cowl. The split line indicates where the bottom cowl is to be trimmed first.
After trimming the bottom cowl split line, and after I get the firewall side of the top cowl trimmed, the plan is to use the bottom cowl to mark the top cowl side trim lines.