You need to start eliminatings possibilities.
1st, you know the fuel pump is fine - so no electric fuel pump needed, just more problems and you don't need that
2nd, try the mason jar trick back at the tank - if it works then the problem is the tank, if not then the problem is the fuel line between the fuel pump and the tank, inspect and replace (I only use Stainless Steel), OEM stuff from Advance Auto I've had fail in less than 2 years and nothing beats the sensation of stepping on the breaks hard and having them go to the floor
3rd, lets do the same thing with the brake line - remove (maybe just loosen)the line from the proportioning valve that goes to the rear brakes, do you have fluid? YES rear brake lines inspect and replace (again SS), no then PV forward, remove the rear line at the masdter cylinder, Fluid Yes tighten and loosen line at PV, fluid yes replace PV, if NO fluid at master cylinder then replace master cylinder.
DO you get the idea? Eliminate and zero in on the problem. Don't get flustered. You're a mechanic. When you used the mason jar you eliminated the fuel pump to the carb, so the problem is the line to the tank or the tank. What did you do when you dropped the tank, could the lines be hooked up incorrectly? Are there 3 lines? I don't remember. The pickup goes to the bottom of the tank, does it. If you reversed the return and the pickup, then you would be sucking air. Nothing like the taste of gas in the morning, but you could blow on the fuel line and should hear bubble in the tank, if not then you probably reversed the two.
You are doing great, just don't listen to the guys at work, they know less then you do. I work with networks and when we have a problem I cut it in half and which side is it on, now cut it in half again and which side is it on, eventually the problem gets small enough the human brain can comprehend. I hope this helps. You are so close to driving it.
My guesses it's your proportioning valve and you reversed the fuel lines, just a guess!