Need some help with a 305 v6

[57taskforce]

I'm working on getting a 66 medium duty Gmc running. I'm not sure of the series of truck, but it has a 305 in it. I need to track down a good carb for it. What did they come with from the factory. The owner told me Someone at some point in time a long while ago rigged a two barrel from the junk yard on it. The original carb is long gone. I'm trying to get it running asap. If there's an aftermarket that will work than I'd look into that route as well.