Griff,
Nothing other than the profile from Uberti or Chaparral is authentic for a standard '73. Everything else, you might see on an original '73 was either special order or after-market, just like today.
The Marbles sight is good choice. I usually recommend a "41W" base with the large brass bead. Most rifles with cowboy ammunition shoot to point of aim with this sight. If, you would like a bead somewhat bigger for tired eyes, I would recommend "The Grabber" front sight offered by Manatee, at bananariveroutitters.com. Manatee has one looks like a door knob ..... perfect.
The Marbles sights usually fit very tight to a Uberti dovetail. "Standard" 3/8 dovetail. Depending on your definition of "standard." I would recommend leaving the rear sight "as is" unless you really don't care for it.
Coffinmaker