Hi Bill,
You didn't mention the standard heat insulation used on the car. Is it missing? You can see it here, item #80 & 81.
https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=28963
It is an "asbestos type" insulating board that partially covers the drivers footwell, firewall, & above the muffler. I think a lot of folks just use 1/4" commercial insulating board. It helps quite a bit to go ahead & cover the spaces such as passenger footwell & the remainder of the drivers footwell that the factory kit does not cover.
I personally used the Moss type kit to cover the original areas & filled in all of the other areas that the kit didn't cover, with two layers of Dynamat Xtreme painted body color. It has held up well to heat for two years. Don't skip the large insulator which goes on the outside of the floor pan & above the muffler.
The two exhaust down pipes are very hot & close to the rest of the car. In researching this subject I came to the conclusion that the conventional pipe wrap heat insulation tapes would eventually cause burnout & corrosion failure of the pipes. Quite a few racers said it does keep the heat in but pipe life was short.
A loose fitting overall cover on the pair of down pipes with air circulation space within could prevent this burnout problem & still keep the heat out of the rest of the car.
I found this shield here:
https://www.mmrusa.com/HSreflectshield.htm
#101420 - 14" X 20"
It is an aluminum covered mat with a flexible ceramic interior.
The 14" x 20" size was just right to fit around the pipe pair & extend from the header junctions to the muffler inlet. Since this blanket can't be cut, I wrapped it around the pipe pair & secured it with a coarse pitch spiral wrap of bailing wire. Painted the thing black to make it less visable.
This shield really keeps the heat away from the passenger compartment & the rest of the car. Possibly the single most effective thing to keep your feet cool. There doesn't appear to be any heat injury to the pipes.
D