"I have a friend that wants to fun a matching set on a 270 gmc." Typo?
Fun? Do you mean "find" a matching Zenith set or "have fun" making a matching Zenith set?
If you want to buy a matching Zenith set then Stovebolt rules say you must post your request in the Truck Parts Wanted Section.
If you need information on how to create/build your own dual matching Zenith set, I would start my education journey here:
https://www.thecarburetorshop.com/Multiplecarburetion.htm