Yes, I did not elect to use the paint on stuff. I used a product called Dampifier Pro. To do this, I scraped all the asphalt/felt crud off of the entire interior of the car. I cleaned down to bare sheetmetal. This was quite a job, but well worth it. I then applied this material to the underside of the roof, all door panels, fire wall, floor pan, just about every place that it could go. I also put in some insulation that I got at Home Deopt. This is a double layer of foil with air bubbles between the foil layers. I put two layers on the sides of the body and three in the ceiling. I tucked this up tight under the edge of the windows so that any water draining through the doors would not touch metal. I stuck the insulation in place with silicone sealant. I installed a black carpet on the floor instead of the rubber mat. Under this I installed additional sound deading padding. The effect is very good. If you tap on the hood which had no sound deading materials on it you get the metalic sound. Tap on any of the other panels and you just get a soft dull thud. The sound deading is supposed to change the resonant frequency of the metal panels. I don't have any rattle, squeaks or anything now when I drive. You can carry on a conversation at 55 MPH without shouting. It is very plesant inside now. Prior to doing this, the interior was noisy and there was lots of engine noise too. Not cheap, but well worth it.
By the way, the main reason that I decided against the paint on stuff was that the process looked too messy and to get the build up, would take a lot of material.
To answer some of your questions more directly, I did put sound deadner in the kick panel areas, behind and under the dash, in the rear of the car in the area to the sides of the rear window, behind the rear seat arm rests, under the rear seat, behind the rear seat, but none in the trunk. I put insulation over all of the interior except the floor where I used a sound deading/pad under the carpet. In short, I covered every surface that I could get access to.
Good Luck,
Rich
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1937 Master Deluxe 4-door Sport Sedan
Restoration project 99% complete
May never get to 100%