First, I deeply encourage you to keep it stock. You should be able to run fast enough for most situations and by merely add a little more time to the trip, if necessary. As the others have advised, it may serve to get a lesser car for hotrodding or whatever.
Second, I have a 50 convertible and I'm contemplating installing a 261 (which in appearance resembles a 235 and the 235 resembles a 261). You get the picture. In addition, I have a 50 Power Glide differential that I may install in any case. The differential torque tube and gears will not easily reveal the change.
Again, do what you want with your car. But, still, it is a shame to change them out to something different. That's why I'm reluctant to make the change in mine. There is a lot to be said for the pleasing feeling you will have in honestly answering when someone asks you if the car is original or not.
Best,
Charlie