With numerous trims and sandings, got cowl to fit well along all edges. Using drop light inside cowl to backlight hing holes, was able to drill into hinge holes along all sides enough to hold hinge halves in place for cowl removal. With cowls removed, could match drill from inside cowl through hinges. Top cowl hinge halfs were epoxied in place using a wet flox slurry. When cured, will clean out holes, then rivet hinges to top cowl.
Using light under cowl to find hinge holes for match drilling into.