Vapor Saver system breather cap.....

I have a '71 Scamp that needs a gas tank. Well, I have a new older model tank that doesn't have the nipple for this line. I'm hoping I can use the older tank and a vented gas cap and do away with the little line to the breather.
Does anyone see any reason this won't work? If it will work I'll use a regular v/c breather.
I'll take a pic of mine and you can see if it's what you are looking for.
Dallas