These are only my suggestions. This is what I would do, with what equipment I have, and with some safety in mind.
You DO NOT want to run anymore tests until a filter is between tank and pump. You don't need and other filter.
Yes, fuel is sucked from tank and pumped into carb bowl.
Test needed:
Hose from fuel pump inlet to a can of gas on the ground. Disconnect fuel line at carb and put into a container. Take off plug wire from distributor center tower. Crank for 15-20 seconds. Should get a good pulsing flow into container. This test will isolate the pump as good or bad. Eliminates all other portions of the system. Report results.
If the above test shows good pump. Attach outlet to carb, plug wire back into distributor and try start. Leave gas can hooked up to pump.
Finish getting tank out, clean it, inspect and install new sender. looks to me like the only sender available is a "universal" style. Your tank was used on 47-48 trucks also.
1. "Buttoned back up". What does this mean? What have you done to motor?
2. Has it started recently?
3. Did you change the pump and take the pump off?
4. Seems like pick up tube does go down to bottom and is said to be welded to bottom? That is probably the worst idea I've heard. Don't know if you can examine that or not. If your tank is a new J. Carter, should be OK. If it's orig, could be busted off/rusted off/plugged. The outlet you speak of has a pipe thread, if your tank is old original, that outlet/pickup tube needs replaced probably, but I have not seen or worked on that tank. For now, the gas tank and all it's lines are eliminated in first tests. Results will tell what the next step/test is.
