I'll play the devils advocate here
I have an electrical pump on my '67. The biggest advantage, you turn the key on and you instantly have fuel pressure without cranking the engine. This is nice because if you don't drive your buggy a lot like me, it automatically fills up the bowls in the carbs without having to crank the engine over and everything is ready to start. And yes, fuel will evaporate out of the carb bowls if it sits for any length of time (seems to be worse on bigger carbs in my experience).
Secondly, I know everyone talks about electrical pumps failing and leaving you stranded, but that argument doesn't get far with me. Ok, here is the engineering side coming out in me. Think about it, there are HUNDREDS of single point failures on your buggy that will leave you stranded, even in stock form. Points, condenser, cap, rotor, coil, tires (do you carry a spare?), brakes, trans, engine, mechanical fuel pump, etc, etc... If you get a good quality electrical pump, you are not worse off than stock IMO.
That being said, there is nothing wrong with mechanical pumps. It really just comes down to a preference. I had some issues with my mechanical pump and switch to electric and have been happy since. That was 7 years ago. Everyone has their own opinions and preferences.