Parts are pretty easy to come by...most are made by Dennis Carpenter (in NC), but if you do a google search for "1965 Ford Thunderbird Parts", you should be able to find a dealer near you. The one I like is National Parts Depot.
And to address the painting...the best thing to do is decide how much you can put into it and get it done for that price...you will get what you pay for...a cheap paint job will run in the $200 - $1000 range, a fair job will be in the $1000 - $2000 range, a good one will cost $3000 - $10,000 while a really good one will be above $20,000. The key is attention to detail.
And as far as the interior goes...if you want to save some money you may want to try it yourself...you can pick up an interior kit which includes, seats, carpet and headliner and install it yourself...
Hope this helps. Good luck and post some pictures once you get it going.