So the engine runs when you pour gas down its throat but won't stay running. How many times did you try it?
I know the pump is easier to prime if the fuel tank is full. If you're almost empty it'll take longer. You can take the fuel line from the pump to the carb off, pull the ignition coil wire off and crank it over to see if your getting fuel. If you're going to change the lines that would be the time to try that.
I assume that the truck ran fine before all the work was done soooo....if you do have fuel coming from the pump, it could be that a small piece of fuel line or pump diaphragm has gotten into the carb.