Correct type gas cap for vapor system.

My challenger only has the filler neck vapor line but being a 71, I assumed it originally had the vapor saver system and was changed out because of the 2 lines going to the front. 1 was fuel supply and other was the vapor line so, I installed the 4 nipple fuel tank and vapor tube which detmatt hooked me up with.
My concern is which fuel cap do I use? I have this type in the pics. Can I use it or do I need a certain type for the vapor system?
Getting real close to finishing this black...

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