There are two oil lines that run to the timing side (right side) of the case for providing oil to and from the crankcase to the oil tank. The breather hose come from the back side of the case between the motor and the gearbox if it is fitted with this type of breather. Stock was just a fitting with a bit of foam or gauze in it. The modification is a reed valve breather that attaches to this spot. Other locations depending upon year for that breather hose is the back side of the timing chest high on the right side behind the cylinder. Or front left off the end of the cam. These lines also run to the oil tank but to the top as opposed to the back side which is wear the actual oiling lines go.
I realize I am visualizing this as though the bike were complete, which from you description it may not be. So you would be looking at a pile of parts perhaps. Regardless, become familiar with either Old Britts web site or Andover Norton as both supply blow up drawings of parts groups and can be really useful for figuring out what you are looking at.
Below number 44 is the breather line. The other two are for oiling. And in the drawing at bottom the typical '72 breather can be seen (#46).