well, i bought a set for my 64 dart because it stated that they did fit early a's in the listing but they don't really. the pass side goes in fine of course but the drivers side will not clear the manual steering box at all. i had to beat a 1" deep dent in the collector to get it to clear, needless to say these are only temporary until i get the money for some fenderwell headers (the car is a beater so i don't care about cutting it).
the real problem however is that the collectors dump out right into the steering linkage and k-member. the down pipes need a sharp 90 out of the collector and we had to squish the pass side into an oval to get it in and out. i should have welded the collector bolts to the flange because getting them into the holes is literally impossible. i have to fish them in with a piece of wire from the bottom. everything involving these headers is a MAJOR ordeal. the only good thing is that if you can manage to get the pipes unbolted from them, they slip out the top pretty easily. also because of the outlet, routing both pipes to one side for clearance under the tranny crossmember becomes a PIA and consequently the car needs to be on a lift in order to have room to rotate the pass. side pipe enough to twist out of where its captured by the linkage and k-member. sucks but they were the only thing i could afford at the time.
my recommendation: avoid the tite-tubes if you have an early a unless you feel like doing a lot of extra work.