I hope you mean I-85? In Atlanta, off of I-20, east of town, north of Conyers- Crane Auto Parts- Alan has about 25-30 mustangs (some sitting on top of others) 770-922-3751. His prices are VERY reasonable. I got a rust-free pass door from a 65 for $75. Off of I-385, south of Greenville about 10-15 miles, there is a places that has dozens of old cars and these suckers are FOR SALE! I saw some nice ones and prices weren't bad. There are some parts, too. In Charlotte, call Don's Mustangs 704-547-0693. he has a few acres of them! Too bad you're not going thru Pensacola. Bob's Mustang Village, just North of I-10 has 5 acres of them all lined up in rows! 850-477-8056. Just to name a few! I just came back from Va & Ga and had an F-250 FULL of parts! Found a flat 71-73 hood (NO rust) for $50 in Va. Been there- got the postcard!
In Atlanta off I-20 near the airport is Metro Mustang http://www.metromustang.com. Large selection of used, NOS and repro parts and a few dozen Mustangs in the back lot. Mustangs Plus is on I-85 in Norcross, north of Atlanta. Not familiar with I-65 (did you mean I-85?), but at the I-85/77 junction in Charlotte is National Parts Depot. On I-77 near Mooresville is Piedmont Mustang and Ford--look for the Mustangs behind the wire fence on the west side of the interstate.
Actually I might go through Pensacola. We are going to BAton Rouge and leaving from there to go to Milton which is to the north on Hwy 87, I think, to place called Stripmasters. They do restoration work and they media blast.