Was the 305 a serpitine type and was it changed to V-Belt, if so your water pump might be reversed. Check the thermostat, even new ones can be defective, pull it put in a pan of water and put it on the stove. Use a therometer to see when it opens. 180 is plenty on a carb engine, maybe 160 out in Cali. These old trucks had a fan shroud for the V-8.
