Cold blooded truck

[truckin 79]

So my 79 is real cold blooded in and out. The truck will srart fine but seems to take at least 10 minutes before it will move. Even then it barely moves just chugs along. I have the exhaust stove pipe set up to direct vacuum. The thermac on air cleaner is wide open as well. Well these 2 things hooked up correctly make a huge difference?
Now to the interior, the truck is a non AC equipped truck. So i can feel heat coming out but not much. Can i put on a stronger blowing fan since it is only a 3 seed switch. I have a 4 core radiator and not sure of temp on thermostat