A trip to pick and pull solved my seat mount problems when I went from bench to bucket seats.
Ford makes a under the bucket seat tray that mounts exactly where the bench seat mounts, AND then has exactly the right bolt holes and nuts for the two bucket seats AND either the package tray or the small fold down jump seat between them. [same bolt pattern , customers choice on jump seat or "gun box" / junk tray.
If you find one of the under the seat trays, your switch from bench to buckets is a bolt up job.. well worth the cost.. I paid $30 for the one I got.. seats were installed in about 20 minutes.