Doc, thanks for the sugestions. Here are some answers:
The shipping weight of a Valiant two-door sedan in 1964 is just 35 pounds less than a 4-door, Not a whole lot...
The '64 Valiant 4-door is 165 pounds lighter than a '64 1/2 Barracuda...
Yes, the back doors are whole. Their proximity to the rear wheels is thought to make getting weight out of them counter-productive. This car is going to be hard enough to hook up with the kind of torque it SHOULD have, and removing weight from the area around the rear wheels probably isn't going to help traction.
An aluminum trunk pan would also make the front/rear weight distribution worse. More traction woes, I'm afraid...
Eventually, I imagine the side glass (which is stock) will be replaced with lexan, and at that time, the regulators will have to go... good idea! :D
Thanks for your interest!