Why not get a piece of plastic tube that size, cut to length and paint it black. Even if your doing a full restoration, no one is going to pull you dash apart to see if its right. Just to see if it work properly.
Id rather spend 5-8 bucks plus shipping and be done with it. Its an extra dash for an ebody convertible so this is just a drop of water in a sea of $$$$$ lol lol