340 coolant trouble

Before you do much more with it.

Tell us about the cooling system, has the radiator been recored, how big is it, are you using a shroud, clutch fan ? what is the initial timing, how hot is it getting, take a thermometer and stick it in the radiator to get a measurement. You mentioned your upper hose blew apart. Does the lower hose get collapsed, is it an old hose as well ? Is the lower hose new with a spring inside it ? What kind of water pump did you put on it, is this an AC car ?

Let us know, we can guide you better that way.