seat mounting and headrest width dimensions

Having just gone through the bucket seats on my '69 Road Runner, replacing the seat tracks, correcting the floor mounting area, and reconditioning the headrests, new seat covers and foam, you would be way ahead to live with your initial problem of no reclining. Put a spacer under the front mounts to till the seat a little.
Headrest centers 8 7/16"
Seat to track front approximately 15 3/4"
Side to side
Rear 15 5/8" side to side
Front to rear 12 1/8"
There are a lot of things with cars that you live just with .