Steve, I just overhauled the driveline and interior in my 50 Styline. I had contemplated changing the firewall padding but changed my mind after seeing everything under the dash needed to come out including the steering column, gear shift, heater, wiper motor, wiring, cables, hand brake, clutch, brake, and gas pedals to say nothing of the front seat. Even though most of these parts were already removed for up-grading and rewiring, I was stymied by the daunting task of removing the steering column. It seems that the Fischer Body assembly sequence required that the insulated pad be installed prior to all the parts, wires, cables, and steering.

A close examination revealed the insulated pad was not in that bad of a condition, however, the rubber skirt that covers the floor carpet-to-firewall pad connection was beyond help. I wound up carefully snipping the threading that holds the crumbling rubber skirt to the bottom of the insulated pad. By gently pulling out the deteriorated rubber I was able to make a template from the pieces. I used the template to trace and cut out a new skirt from a roll of neoprene that I purchased on-line. After a trial fitting of the new piece, I used a tube of 3M drip check sealer to permanently glue the skirt to the pad.

The fix worked out really nicely, and the repair stood up well to a good deal of tugging and pulling when the carpet was tucked back up under the skirt. I did have to remove the heater duct extension from the heater assembly in order to work the rubber into that area over the transmission hump, and I wouldn't want to try doing the job without removing the front seat. It took two days to do this part of the interior, however, I am satisfied with the results if not a bit sore from all the crawling around.

Hopefully your firewall pad isn't so badly beat up that you can salvage it as I was able to do. The alternative is a daunting task better left for the day the car is going to be gutted and put on a rotisserie. Bob

My pad had extra holes and not in the shape I needed considering it's a complete restoration. all the items you mentioned are out. I purchased a new pad from  " Quietride Solutions". Excellent quality . Still have to install it but lots of other things to do . I did not not have a rotisserie but removed the body and was able to put it on it's side on a foam mattress mounted on a rolling frame.

Whatever works. As the old saying goes, where there's a will, there's a way.