SUSPENSION GOT ME BEAT.
Very cool of you to take the time to write all that...much appreciated..!!
I did find a YouTube vid of a 73 Dart suspension job that looks like it'll be helpful..
shoot man, if you were local i'd come over and help you bang it out. or at least drink all your beer and tell you why you're doing it wrong.
watch a few vids. re-read the FSM and think about approaching it from an assembly or repair standpoint and how each component works within the system. sometimes that can help.
don't get frustrated if you have to take it all apart and do it again, we all have at some point.
go slow, be methodical. torque everything to spec. don't forget the cotter pins. if you get stuck, ask questions.
oh, and the only real differences on the 73 dart from your 72: the strut rod bushings are different and more of a pain on the earlier cars, the calipers bolt to the spindle on 72 and down, and to a caliper bracket for 73+. some of the tie rods/pitman/idler arm mounts are different loading from the top or bottom, pay special attention here and reference the FSM for the correct way.
it's physically demanding work, but it's also very straight forward once you figure it out.
oh, and don't forget the cotter pins.