I ran a Motorcraft 2 barrel carb on my 250 for a while, on the stock manifold. with a couple adapters it fit nice. It is a lot more adjustable and friendly that the 1 barrel ones. Best one is the Morotorcraft 2150, It has a big base like a 4 barrel but you can adapt it easily. Had to use a low profile air cleaner do to hood clearance. Read stuff from Eagle research and his opinion is that the motorcraft 2 barrel was one of the most efficient OEM designs made. I think they were actually made by holly. Lots of them available on ebay for cheap or expensive.
