I am looking to see what everyone is using for door vapor barriers and how you are affixing it to the door.

I have not seen any kits available, and I assume most attach it with butyl of some sort.

Also, has anyone used an upgraded material? Modern cars use a foam sheet that offers an additional layer of sound deadening at the same time, I'd love to find something that worked in that manner as well.

'72 'Cuda

Performance car graphics has kits for some mopars

you are limited by your imagination.
if i were doing this i would just find the thickest plastic film i could buy and attach with strip calk.
then find some thin sound deadening for under the carpet then trim to fit under the trim panels..

I just used a 6 mil poly sheet from home depot. The original caulk was a string caulking. I just rolled plumbers putty into thin strands and used that. Once installed, it looked pretty close to original. I also sprayed sound deadener in the doors. I think the issue with using a foam is that it will keep the door panel from sitting flush against the door shell. Though on an e-body, I don't think you will have that issue due to the way the door panels screw on. For a b-body using the fiber board cards, it would be more of an issue.

Normal vapour barrier you buy at Home Depot should work and is cheap.
I usually put it on with dum dum caulk or spray adhesive which is a lot quicker and looks more factory for a lot of stuff but obviously has to be re-applied the next time you peel the plastic back.

Don't use silicone on the plastic sheets barriers, the plastic will fall off and it will be impossible to remove the leftover silicone without taking the paint off the inner door panels--that was my mistake.

I upgraded mine using the double-foil-sided insulating mat from Speedway Motors and taped it along the edges of the door, just short of the plastic door panel using the aluminum ducting tape with the foil backing.

It has a fluffy, flame resistant matting that really cuts down on noise, fumes and heat. I cocooned my entire interior with that and Dynamat Extreme. The car sound like your sitting in a bank vault when you close the doors. It really trips people out when they sit in it.

I lost my pictures of the installed product when my computer died.

Go by a mattress store & garbage pick one of the thick plastic bags they come in all the plastic you'll ever need,prefit the plastic making all the necessary trim cuts/openings,3M spray adhesive & using a piece of cardboard to block/direct the spray pattern where you want it.