As Snyder is the only spring maker I am aware of I checked their part numbers and find 1940 Coupe does not interchange with 1940 Tudor and that 1940 Standard Tudor uses a different seat cushion spring than DeLuxe in 1940.
Here are some photos of my Deluxe 40 coupe seat and springs from 1988. Each coil spring for the bottom bench seat cushion was encased inside it's own separate burlap bag. The backrest cushion springs were not inside any bags. Lots of batting and padding was used between springs and top covering fabric. As I recall hog rings were used to keep seat springs in place. backrest springs were held in place buy crimped clips. Experienced upholsterers would know for sure. Last photo is of reupholstered bench seat using LB kit. I did this in 1988 so memory is not crystal clear.