This is just a suggestion, but some of this stuff you will not find NOS. If you do, you'll pay dearly. So what I'm going suggest to help you out, because this is what I did.
Bench seat, find one in a local salvage yard and have it re-uphoulstered. Use this web-site.
http://www.car-part.com. The upholstery comes from
https://www.miamicorp.com
Carpet. You can get one from
http://www.brotherstrucks.com/81-87-...o/CPT81PU%2DS/.
Door Panels.
http://www.lmctruck.com/features/cc/CCCKC.htm
If you like to see some pics of these actual parts installed, let me know, I can post them.