I was hoping CB890 would step up on this one. I am thinking about it. The fix should not be all that difficult, it needs an organised approach.
I would suggest starting to eliminate the possibilities at the fuel tank. Is there any fuel flow when a suction is applied to the fuel line? If not start there with the fix. Get all of the old steel line out, CAREFULLY, and replicate it on a work bench.
Without a plan that follows the fuel and then the spark everything is just a random shot in the dark. If a person gets this truck running, by chance, and not know what they did, the situation could rise again. Where would a person start the fix again?
A person should remember, a spark ignited engine does not run on gasoline. Gasoline will not burn without proper vaporization to get oxygen in the mix. I do not like to see gasoline poured down and into a carburetor, unless the fuel is going into the carburetor bowl where it can pass through the jets.
Rather than fret over the fuel line going up and over the frame, it is more important to insure the fuel line is not leaking. Old age and time will cause the fuel lines to corrode through from the inside to the outside.
If you do not have some diagnostic tools like a vacuum hand pump, buy one.
https://www.google.ca/search?q=hand+ope ... 1200&hl=en