Hooking up a heater.

[Dave]

There is a water hose that goes up and across the top of the engine that comes off the bottom radiator hose right before the water pump. It makes a u turn at the back of the engine and goes to what im not sure.
(A cooler for something, pardon my ignorance).
Can I use that to hook up my heater through the dash?
It looks like it goes to the back of the engine for just that purpose. As well as the four plugged holes in the firewall for access.
Also, I think the flow must be running right to left as you are standing in front of the vehicle?
Any help would be very appreciated!