Those are emission parts, and are specific to the car year, model, and engine. They are extremely difficult to find, and if you find used ones, they are probably not going to be in much better shape than the ones you presently have. One of the problems with emission parts is that they all look similar, but have different working specifications.
These parts were part of the dealer initial stocking order when the cars were new, but were rarely needed unless they were damaged by an accident. Once they became "dead" inventory, they were returned to the manufacturer for credit, or the dealership disposed of them along with the other obsolete parts inventory. This is how swap meet vendors got their NOS inventory. Then when they were actually needed because of old age, they were discontinued by the auto manufacturer, hence the difficulty in finding them.
They can be removed with no harm and the holes in the engine block can be closed by using small freeze plugs. If your engine requires the air injection pump to have a belt run over it, then you just allow the pump to blow air to the atmosphere. I have been told, but have never tried it, that you can remove the vanes from the pump, and then close up the cross over tube, and eliminate the working system, and still have it look original with all the parts. The pump at that point just becomes an idler pulley assembly.