Crank it with the line off the carburetor or before filter, if you get fuel then the jets in the carburetor are iced up, no fuel then it’s iced before the pump then take the line loose before the pump, thaw it out with the ol hair dryer, heat gun, what ever non flammable
handy item ya got, when it starts dripping if it does let it run out a bit then hook it up and fire it up.
Stick some gas line antifreeze in it, ethanol I wouldn’t recommend with a ‘78 model.