spudz,
The tube running to the junction block on the firewall is a straightforward vacuum line to the hdydrovac and evidently, a auxiliary storage tank. It should have a check valve in it somewhere that won't allow vacuum to bleed off.
The other line I don't understand. It would appear that the oil fill cap on the valve cover is the ONLY means the engine has to breath, and it is doing it with vigor...all over the valve cover.
I wonder if your rig was a old Southern Pacific service truck. There would probably be SP tags on it somewhere.
Keep us posted.
Stuart
