73 and up disc on a 65 dart

Any time the geometry changes the toe can change as well. Since the 73+ disks widen the track width compared to your old set up, a change in toe is normal, and toe out is what you would get with the tie rods now being too short.
yep i had the same thing with mine. A search on here and you will find the string alignment method it was surprisingly accurate. i did mine and it was barely off when i had it aligned.