I think you'll have to make something, they don't make snorkles for carbs. there is so much to a carb to make ue everything is sealed up that isn't there on an EFI that the companies that make the snorkles don't want to take on the liability.
It can be done, I had a carbed '79 Dodge that was snorkled over the cab and would run as long as the top of the snorkle was still out of the water, it just took some work and allot of silicone caulking and duct tapeto get it there.