What exercises help with pectus excavatum to make one look more regular?

None.: Pectus is a problem of the cartilages between the ribs and the sternum. Sometimes equal on both side, sometimes one side worse than the other. Not really made better by exercise, but well-developed and symmetric pectoralis muscles and well-developed abdominal muscles ("six-pack") can distract viewers from the pectus. E.G. If mr. Olympia had a pectus, would anyone notice?