That paper is made from unobtanium. Some materials are just not available anymore. I've been researching for 2 years to find a very similar material for that and for some other similar brown paper. The brown paper is called "brown asbestos felt". Yep the stuff on the firewall and kick panel insulation and the gas tank pads are asbestos. They have the big A in a circle logo from Armstrong. The same Armstrong flooring that went bankrupt because of asbestos insulation products and tile flooring.

I was actually in contact with a company today to see how they were coming with samples of my fake "brown asbestos felt" paper. If the samples look good I'll have to buy 1/4 semi load of the stuff for them to make it in qty. I asked if they can do a similar black version like your application.