ADDING A 4BBL..HELP Please !!!

A 4bbl shouldnt affect driveabillity any at all or it may even improve because I know you are running a 1920 and I couldnt get my car to run worth a crap with that carb on it. As long as you keep the carb size small and jet it properly I don't think you will have any problems.

Just because you couldn't get a 1920 to run good doesn't mean it is a bad choice for a slant. They made a few million slants with the 1920 and I am willing to bet they all ran pretty good when they left the dealership. Even with a 390cfm carb it will be overcarbed if everything else is left stock. The slant intake does have fuel distrubtions issue which are not going to fixed with a bigger carb. I would like to know what the intentions of the original poster are. They are many many cars that have had parts hung on them for no better reason than peer pressure. In my book more horsepower is always behind chassis/safety improvements in terms of importance.