Front back rest spring measures 23" by 44", approximately. No wood.
Metal surround with slides.
If you are missing everything, and can't find an original front seat assembly, then i would suggest you find a front bench seat from any old car that will fit your s/w. Photos of what you do have would help us help you. Photos are of our 160-A. Sounds like you have a 160-B, with dome light in rear. Our dome light is mid ships, which makes it a 160-A, My guess is that Ford used the same seat frames in all the 160 series sedans. Fabrics varied, of course. Others may know more than I do about this.