Went to the bookshelf several times this weekend. Swear I looked at the same stuff over and over. tried again and found this early this morning before going to work. Cannot verify the accuracy of what is shown here (Bad pictures of bad PDFs in a fairly good book), but it looks informative. Hope this helps.
Pics are of diagrams for 1973 EGR Equipped 351C in several combinations, (2V/4V, MT/AT, W and W/O AC). Still has some things like the air cleaner that do not look correct, but they do show 2 and 3 port temp switches, 4 port loop on the firewall, mechanical DVAC for manual transmissions, etc.
Have PDFs attached below of these and the 302 and 250. Think if you combine this with the calibrations that Don C has, it just may get you where you are trying to go.
I don't understand why there are 2 options for the heater hose mounted 2 port switch when having the auto transmission. Attached are pictured that show one type for the auto trans (18B402), don't know what the optional PN 18599 looks like. The other picture is for the manual trans (18A568). PN 18599 images I can find don't make sense to me. I got these pics from other members when I was trying to figure out how the vacuum lines ran on my 73.
Here is the link to that post:
https://www.7173mustangs.com/thread-temperature-control-valve-in-our-heater-hose
Also pic of the vacuum tree in the rear of the intake.
1973 EGR Vacuum Routing.pdf