How should I handle crown molding on bowed walls and uneven ceiling?
Here is what a good carpenter and a follow up painter/drywall finisher would do. Install your crown molding/ don’t try to suck it in at dips in wall. Where your joints meet, just shim behing them and then cut your shims off even with bottom of crown molding. Now I would take a 12″ wide drywall knife and fill the low places in wall from the crown molding down about 16″. The difference in the ceiling can be caulked. Yes 3/4″ is a little big to caulk, however I think the crown mold will overcome the dip in the ceiling,and even in the walls if you decide not to skim out dips in wall with drywall compound.
