Help with 72 350 Engine comparment details - original/stock

[72 GMC Longstep]

I am trying to get everthing under the hood of my truck back to original and I need some help with this. At some point I might remove the engine and reseal it and paint it, but for now I want to get all the hoses, wires, etc back to original locations etc.

The truck is a 1972 GMC 350 4bbl automatic truck. I will post a few pictures of the engine comparment and feel free to comment on how what is correct or not. Or even better if someone has pictures of a proper resto or original truck that would be even better.

Some of the specific questions I have are:

1) what is the little clip located to the left of the choke thermostat for? It is bolted under an intake manifold bolt. Is it for the vacuum advance tube?

2) The vacuum advance tube routiing appears wrong, How should it look?

3) Why do I have the RH exhaust manifold with plugged holes for an AIR system and the LH with none? Would this truck have come with an AIR pump? I find no brackets but there is an empty groove on the water pump pulley.

4) What are the plates/brackets mounted to the frame right beside the exhaust manifolds for? Are they bent out a little? maybe to help with spark plug changes.

Again feel free to comment on anything that is not correct. Thanks for any input