I have a 89 C1500 350 v8 farm truck thats been sitting for a while. Im pretty sure this is a blown head gasket. Water shoots out of the exhaust, white smoke, and water keeps gushing out of the radiator cap. I need a second opinion bc the oil is not milky and it only just now started to run hot. I replaced the thermostat and the temperature fluctuates between 180 and 240. Below is a video of me revving the truck up. You can see water shoot out and it gets really smokey.
Google Drive Video

 

head gaskets can fail in various ways. You don't always get milky oil.




Get yourself a test kit

 

No need to worry thats a blown headgasket

 

Defintely a head gasket i have a 96 c1500 did the same thing