POR15 Undercoating Spray
Can't comment on the POR 15 system top coat, have to believe that your window would be small in most locations. POR 15 from what I recall needs moisture to cure therefore the desert may not be your friend, although we have had some rain lately not sure if the moisture level is enough. I applied two part epoxy on my chassis, followed by 3M undercoat and then top coated with a two part catalyzed zero gloss urethane. Bottom was completely done except for the front wheel wells. Great for noise reduction, and virtually reduces stone marks. As for undercoating in general, I have 3 65's and two were undercoated. I can't say for sure that this was done in the factory, but in both cases undercoat was present under the gas tank, I don't know of any dealer etc who would go to the expense and trouble of tank removal to apply undercoat. Both of these cars were from the Pontiac plant which is rust belt area. My only comment is unless you are building this car to qualify for judging; it's your car build/restore it the way you want.