Reducing unwanted heat in cab

[graymond1967]

I have a 67 with factory air, not presently working, but the heater core is throwing off a lot of heat. The floor has been insulated with dynomat and it is staying cool.

How have you guys/girls dealt with this?

Insulate the outside of the heater box?

Put a valve in the heater hose by the manifold to turn off the fluid?

Does the vintage air system work better for heat than the stock system?

I am putting a serpentine system on the truck to get rid of the drive belts. So I am open to options.

Truck is a 67 with a 502 big block with headers. Currently I have about 10 to 15 inches of vacuum at idle.

Ray