for busses with air brakes, i think it is a good idea to put a fitting by the aux tank so that you can run a large air hose to a one inch air wrench so you can change tires, use the air jack, etc. That is what i did, and i occasionally use the bus air to pump up tires, etc, and on my last coach bus, i used the bus air to paint the thing...
(I also made a 6 foot long compartment by the tanks to hold all my air tools, hoses and so forth...)
As far as your posted compressor, it looks ok to me.
Jesus Christ... Conversion in progress.