On removing the old skylight found two problems. 1. The drywall extends about 5/8" above the curb due to an offset in the old frame. 2. Some of the flashing is folded over the top of the curb (not every piece).

Obviously the Velux would not fit and seal. The drywall can be trimmed. What is best way to trim flush with top of curb? Saw or score and break off? Concerned about appearance.

It looks like a sloppy job by the roofer on original roof to leave some flashing folded over the top of the curb.
Wouldn't it be ok to trim flush with top of curb? There are no water leaks with the current curb. There is no gasket or seal between the skylight frame and top of curb. This may be causing a lot of the condensation on the frame and air inflitration?

The Velux does look like a much better skylight. What would be a fair labor cost to trim the drywall and flashing and install the skylight? The roof is steep but easily reached from the driveway with a long ladder.

Thanks,