Ahh, the memories...
This isn't a show car, but will give you an idea.
We lined front of foot boxes & inside tunnel with woven mat insulation that Snake Bite sells. Then attached aluminium heat shields to front & sides of foot boxes, approx 5 mm air gap. Used hi-temp silicone to attach woven mat.
I'll be using the same woven mat insulation for under rear clip on the GT40.