Best way to get a flip top gas cap on a dart

i have seen a number of darts around the vastness of FABO with cuda flip top gas caps on them.

so my question is:

to get a cuda gas cap on my dart, do i need the gas tube from a cuda as well.

and also do i need to cut into the 1/4 to make reliefs for the hinge and tab? if i do thats ok ...i have the car down for paint now.

what is the best way to approach this ?