Three things to check.
One, look closely at the block deck around the engine to be sure it's not the head gasket leaking. Remember, those engines are slanted back when in the vehicle and the antifreeze/water runs to the back.
Second, why run a hose from the thermostat housing around to the water pump. Just block the holes with pipe plugs. Then, all of the water goes into the block. It's just another place for a leak or a hose to kink or break.
Third, pull the thermostat and drill a 1/8 inch hole in the flange of the thermostat for the air in the system to escape. This will put more water into the system and in theroy, you shouldn't have to add any after the first fill up. Be sure to get it in the clear away from the gasket and flange.
