1962 Valiant Parts
You can use sillplates out of any 2dr '60-66 in your '62 Signet. Slant six was correct that the profile shapes are the same however they are not identical. Starting in '63 the sill plates are longer at the rear but can easily be cut to length. Another difference was one of the screw holes going thru the floor/sill did not line up and required redrilling the '62 floor sill. This info was learned by using '65 Dart GT sill plates in my '62 Signet driver. Also confirmed comparison with a set of the repopped sill plates from a '66 Cuda I was putting a carpet kit in at the time. They required the same mods as the '65 Dart GT sill plates for use in the '62.