I bought some new drip rails from this guy yesterday, "Mustang Parts New and Used" (714) 997-2000 Orange, CA
Older guy, hours not consistent, 9am-5pm. He has used parts available or may be able to locate them. He's a one man operation with a warehouse full of jumbled parts.
Also try Mustangs and Fast Fords, Santa Ana, CA. (714) 850-1500 They do restorations and may be able to locate some. (High priced and a little arrogant, but if they have what you need.)