65 model year and older, your Comet & Falcons are "sister cars" (year-by-year. FWIW: 66-69 Comet same as Fairlane, again, year-for-year)
COMET by Mercury
FALCON by Ford
Trim items differ significantly but your major components should be all the same.
Naturally, for Concours, you should consult your Master Parts Catalog to be absolutely sure there were not running changes but usually, if you stick really close within the same year, you ought to be OK.