Question about gas tank vents 4 vs. 1

When I was planning on replacing my trunk pan in my 1971 Demon, my plan was to go a head replace the 7 1/4 rearend with an 8 3/4 which is complete and my gas tank. I purchased one that has one vent tube, not knowing that there were two types to choose from. Last week when I pulled my old tank out it had 4 vents coming out and going to a steel tube about 1 1/2" diameter next to the gas fill tube. I also noticed that their is a vent line that follows the fuel line up the passengers side of the engine compartment. I have replaced the slant six with a 340. I have also bought the bigger 3/8" fuel line. Did the V8's come with one vent tube? And does the hose for the one vent tube go to the steel tube mentioned earlier or does it go somewhere else?
My question now is can I still use the one I have.
Thanks for any feed back on this
TAZZ