Buchanan is a little too socially conservative for my taste. I'd be willing to bet if they ran on the same ticket, it would turn off more people than it would gain.
RP is extremely socially conservative--personally. I think Buchanan is the same way. They both highly respect the Constitution, though and would make a good team, IMHO.
We don't want that guy as vp. He is too polarizing and will steal all the headlines.
We want someone who is modest and relatively unknown but above reproach. Napolitano would be very good choice in my opinion. The judge has backbone and is very respected by most conservatives.
I don't trust Buchanan. He likes attention way too much.