I’m glad the part arrived as expected.
Whew!
When I got my 71 it would only reach 3/4 full on the gauge and went well below empty on both tanks.
Bought brand new sending units from the Ford dealer (this was back in the late 70s) and they read exactly the same when connected to my wiring.
I went through the same routine on both the originals and the new ones, bending and tweaking. Not only the arm, but the stops themselves a little bit.
Mostly where the rods passed over the stops and got them to read perfectly.
Ended up reusing the originals and they never varied from that perfect reading as long as I had them.
So mine was probably slightly off right from the factory. But after tweaking the gauge read exactly where I liked. Just slightly over full when I topped the tank off and slightly under empty when they were bone dry.
Personally I would test your newly adjusted sending unit out of the tank manually.
Save you the trouble of having to remove and re-tweak things if it doesn’t read perfectly with your 50 year old gauge and wiring.