I'd say if the freeby carbs are new or rebuilt, this is a huge plus. Most are so worn around the throttle shafts they suck air. Also make sure they are exactly the same, bolt spacing to manifold also check throttle bore size. They made a zillion Rochesters for every car and truck, so check this out. Install rebuild kits, read the instructions closely, especially check floats and float setting. Make sure jet sizes are also the same.
If your local guy is really good with cast iron, I'd let him split the exhaust, this way you know it will fit your motor.
