No one single place for all comes to mind.
I always shop around for the best prices including shipping but some of the usual places are:
www.summitracing.comwww.78ta.com (check out the "store" section for interior (carpet, seat upholstery, door panels, etc) stuff, etc)
www.rockauto.comwww.amesperf.comwww.classicindustries.comwww.fbodywarehouse.com (new and used parts)
And of course there are many other options...deals may also be found on ebay or your local craigslist
You will get varied opinions on weatherstripping but some of the main makers are:
www.soffseal.comwww.metrommp.comOne choice for dash pad restoration is:
www.justdashes.com($$$)
Also OER has re-introduced their reproduction dash pad to the market...I'm sure there is a waiting list for some time since some customers have waited on the back-order list for years but it would be less expensive than the above. Some of the above mentioned parts companies should start stocking them again....hopefully.
If your current dash isn't too bad, you may be able to repair it yourself.
