Advice wanted on venting my gas tank

[Yukon Jack]

Here is the gas tank on my 69 K20.



Here is a threaded fitting on the top passenger side of the tank where I can attach a line to vent the tank.



Would like suggestions on how I should vent the tank. If I just put a copper line running down will that cause an evaporation problem? Should I put some sort of breather on the line? A friend suggested drilling a hole in the headache rack support and put the line in there and have it pointing up.

Let's here some suggestions please.