Ricardo,
I misinterpreted your question. I am surprised that this question got on page 2 and no one followed up.
You seem be inquiring about the plates not the sides. Right?
The arching of the plates will determine how they can be glued to the rib outline. Laminated plates are either flat in the whole upper bout, arched everywhere except in the cutaway section or completely customized to a specific pattern. Have a look at a Gibson ES 335, there is arching in the horns but they are flat where they attach to the kerfing.
The laminated plates I make vary. I have one pattern called single cutaway where the top and back molds are flat in the cutaway section where the kerfing would go on most patterns. This would include a gibson Es 175 pattern.
So you just make sure that the plate is going to be flat where you glue down to the rib/kerfing.