Fiberglass doors seem to be the easiest way to go when removing weight right at front and center of region #2, but fiberglass doors are usually a mess right from the mold and need a lot of work for proper fit and function. If the car is of a hardtop variety with no upper post bridge to hold in place a glass pane, lots of frame work has to be had to accommodate that glass usually with ugly or revealing results. I'd like to think that some folks on here are trying to be low key with their respective programs. Fiberglass is also prone to cracking or wearing out fast if careful handling during use aren't considered.
I've never weighed them, but they are light and only a couple of fiberglass companies (open for debate) are reputable molders and shippers. I would suspect that glass doors are in the 8-12 Lbs range in naked form with no internals.
Steel doors for B-cars below 1970 whether they be post sedan or hardtop open air types aren't as heavy as many may think. They each weigh anywhere between 32-40 Lbs naked. The 1971 and later B cars are a different breed and as a result, had longer doors with some even having inner crash beams installed starting sometime in late '72 into '73, thus, they are heavier and bulkier. This is not to say that these cars can't be unloaded of their loads, but one just has to go through a more scrutinizing process to do so.
Removing all sound deadener or rust proofing material from the inner sides cuts weight down on any car, but it doesn't come without some serious elbow grease along with some nasty cuts from those inner door panels.
Surgically and strategically cutting out unnecessary inner door panel material without hampering the function of the windows can toss a little over a pound out the widow itself, but is it worth it? I thought so. This was many years back following on the concept that every ounce counts.
On the other hand, cutting out the main bulk of that inner panel (like DVW has on his '64) can remove a few pounds at least and even more with the removal of the rooster crank system altogether. Only thing is that if you want the window to function like the factory intended it to, you have to fabricate a lightweight system like DVW's and keeping in mind that this only works best on post/sedan doors.
That being said, stock doors that get a chemical milling make the best sense while remembering that these doors are actually starting to get scarce.
I'm not trying to showboat here, but as far as '64-'65 B cars are concerned, the next best option would be the rare '65 A-990 thin steel gauge doors. Problem is: Try and find a pair.
If you really get luck on your side, the '64 A-865 Race Hemi aluminum doors are the next best lightweight option that comes close in fiberglass weight territory. Problem is: You won't find a pair without them being tethered to an entire aluminum front end.
These are post sedan types and are exact duplicates of their steel counterparts. They were only offered on the Race Hemi package cars and not on the Max Wedge cars which by early '64 were already being phased out in favor of the incoming elephants.
For comparison sake, a factory steel door in naked form is more or less 39-1/2 Lbs. An aluminum door in naked form is exactly 15-1/2 lbs. A true 48 pound difference when you factor in a pair.
Back in '90-'91, I dropped the ball on a pair of NOS aluminum jammies in their Chrysler boxes and never saw another set that were anywhere near decent used-uncut-unmolested condition until 22 years later when these pups came along. As you can see, there were a lot of small pockmark dents on them, probably from curiosity as to their alloy skins. Other than that, they were mint and my friend "The Palm Reader" excellently restored them to their smooth surfaces with little to no body hammering and putty.
This single aluminum door comes in at a poultry 15-1/2 Lbs in naked form, but wait!.............there's more to this than meets the naked eye.
