Those LCA’s in the picture aren’t from a ‘73. The sway bar mounting tabs are in the 67-72 location.
Normally the LCA’s aren’t mentioned because the non sway bar tabbed LCA’s are the same 67-76, there’s no need to change them with the brake swap. Generally if they have sway bar tabs you want to keep them matched to the K-frame because the sway bar mounting locations are different and the sway bars have to be matched to the K frame.