Look on the side of the radiator.. it has a hot and cold level... well below the height of the top hose and theromstat housing....it is not a vaccuum , it has air in it....
I have never had a air lock ...except on a LPG engine that had the converter (heated with engine coolant) above the height of the radiator and top hose....With and air lock in there and since doesnt get full coolant flow to flush, yes water can stop flowing, the expansion and drop of LPG pressure will cause it to freeze full (yep covered in ice) and car not run...
The only time an air lock has been and issue....
Jacking up the front... better still park on a slop facing up sorts that....
The bottom hose is 2 yrs old....so are we assuming it is ok then ?
Successful Trouble shooting... is no assumptions.....It is knowing.
Thu I have never seen air lock on early chevs, doesnt mean it cant happen....
U have noted u never drilled the thermostat....so it doesnt have ANY hole, even it it has a little thing hanging in it?.... have u Drilled it it 3/16" yet?
Jack the front up and fill....as Steiner says above...done that?
Is it normal to have the top hose swallowed by air?
Yeah if the hose is old and weak, and its not air, it is pressure in the system....
Have u done a full routine maintance on the system yet?
Full flush, back flush... described in older posta many times
Complete these basic things which is 1st stop routine with any run hot/ over heating issue.
hole in thermostat.... check thermostat is working corectly in a jug
check bottom hose (all hoses)
Check behind the stopcock
Cooling system routine maintance, back flush, water pump/ clutch bearing play
HC/ CO check of the radiator gases.