OK, as I understand it, this problem did not exist until You had the trunk pan replaced. That can mean the following;
1) They bent the line out of their way while working, kinking it and restricting the flow of fuel even after bending it back.
2) With it disconnected, debris got into the line/hose and ended up somewhere between the tank & pump.
3) It is just a stone-stupid coincidence, and has nothing to do with Your problem.
As far as what You've already done;
1) Almost an entirely new fuel system save for the OE hard-lines & carb. You've adjusted the float level, why, and what adjustment was needed if any?
2) Run the car with the fuel cap off,......Driving the vehicle, or just sitting still? It stalled without the fuel cap, correct?
What I doubt is the issue;
1) Hoses hooked up wrong. It would've been difficult to do in the first place, and the lines are different sizes. The vent tube is at the very top of the tank, & unless the
tank was filled to the brim, You wouldn't be getting any fuel period.
2) Tank venting. Besides the cap off test, if the tank had developed a vacuum that stopped the flow of fuel, simply removing the cap would allow atmosphere in at once,
with the accompanying "suction release" sound. The pump would be able to re-establish flow fairly quickly, not 15 minutes.
3) Pinholes in the fuel line. While they can cause aeration of the fuel, they wouldn't allow for the vehicle to drive 15-30 minutes before rearing their ugly head. There
should be signs of excessive foaming in the filter, & the supply of fuel would be inconsistent with a "lean surge" like driveability issue coming & going. Hot or cold.