If they are really off, you could return them...
1. use more gaskets at the same time
2. Grind as needed
3. two part Epoxy glue between the gasket and the sink. then lightly tighten until glue sets (24 hours) then tighten
I would not suggest caulk since it is not water-tight unless completely cured (several weeks?)
Edit: I am assuming you mean the underside since small leaks on the top side would not be a problem.