I used the aluminum backed, rubber flashing from Home Depot on the firewall/toeboard/floor on my '49 and I get no heat from the engine into the cab. It is much quieter than my very sound and nearly original '50. I had a problem getting it to stick to the underside of the cowl near the bottom of the windshield. I would recommend applying contact cement there prior to installing the flashing there. BTW, The stuff has no smell to it at all even in the heat of the summer.
As far as the inside of the doors, the access holes for the doors are too small for applying the sticky sheets in there. I tried and I ended up with angry, wadded up balls of stickiness.
I am going to use Herculiner in there on the '52 I am currently building. I will use a small brush and a small cup which can stay inside the door to help keep the mess down.
