Hi Christen,
The 65 Chevelle was the first year that a 396 Big Block (Code IX) was used (only very few) in a Chevelle. All 64's had str. 6's or small block V8's. There is a small chance you may have to do some slight modifications for headers/exhaust manifolds. Another consideration, some folks dont use any inner fender moldings with large block cars.
The inner fender wells you seek plus fasteners can be found in California nearest you, you can try OPG (Original parts group) out of Huntington Bch, but you will have to pay tax, but you can get em quickly and perhaps in plastic too. Their website is:
https://www.opgi.com/GateChev4.asp
You can also try Billy G's racing out of Texas and pay no tax (internet sale), but you have to e-mail them a request since the Chevelle parts are not listed, but they can get em' cheap, plus fair prices on engine parts at :
http://www.billygrahamracing.com or you can try NPD (National parts depot) at:
http://www.nationalpartsdepot.com/
Good luck. I am not a rep of any of these companies. I have learned from experience since I have bought many parts, who treats you right and who is over priced.