Hi Gig,
It isn't for aesthetics nor period correctness. The Rochester is what would have come originally on the engine. The two carburetors are different designs and certain factors in the Carter might be more appealing. The idle system is different, the cruise system is different and the power system is different if you compare the two. Some people think the Carter will work better and have fewer problems, but in fairness there are a lot of people who are fans of the Rochesters and lots of them are still in use. There are some challenges in them, and actually I'm working now to try to solve one of them. There is a ton of information here about the whole Rochester v Carter thing. There isn't any rush but sometime you might want to read through some of it and that way you can decide what makes the most sense to you.
