Heat insulation recommendations to put over sound deadener?

[msg]

I just covered the floor of my 66 C10, firewall and under the dash with butyl aluminum sound deadener but there wont be much help with the heat insulation from it. What should I go with in between that and the carpet to pad it without thickening things up so much I cant install the carpet? I already have the firewall pad kit ordered and plan to install that also.