which manufacturer seems to have the best carpeting, with pad, and floor insulation, as well as front bucket seat covers for a 1971 mustang?  

It's pretty much a well know fact in the classic mustang restoration world that LMI makes the best seat covers.  I replaced the originals 10 years ago with the LMI's and they still look new today, and I drive my 65 every day.  As far as carpet, I just orded whatever NPD had and it has held up very well.  NPD is a dealer for both the LMI seat covers and the good carpet.  Copy this addy down and get with them.  
http://www.mustangupholstery.com/dealerlocator_usacentral.html