Carburator D150 1983

I am buying a Dodge D150 Ram Custom. 1983. Seller says it needs a carb. This is a single barrel carb. How difficult is it to rebuilt. I never rebuilt a truck carb but I did 1 on a 55HP outboard. Or how much labor timewise would a shop charge to do this. Has anyone had a carb of this type rebuilt before? If so how much did it cost?

Seller said it will only start if he pours gas in the carb. Could the problem be a fuel pump problem and not the carb?
thanks you