I picked up a 1961 F-250 late July and drove her 2,000 miles home over the Rockies and across the plains in 95 F heat. All went reasonably well given any number of getting to know you surprises. I was doing 10 - 15 mpg at about 60 mph. Idle could get rough and fall out after hours of hot running. Couple mornings it was hard to start after a day's work. So I am suspecting a leaky manifold gasket and the carb could use replace/ rebuild. This is the 223 cu 6 cyl with a 1bc carburetor. The only markings I can find on the carburetor are: 12 R 1958.
So can anyone help with the following questions:

1. What is the carburetor on the F-250?
2. What replacement carburetors can installed (and where can I find those)?
3. Where can I get a rebuild kit for the existing carburetor?

Thanks so much for the help. I think it will make a difference.