Alan-
Your initial post was kind of confusing to me also. I think now I understand what you are doing. First, the '36 exterior fuel line goes in the side of the tank well above the bottom but what you don't see is a tube inside the tank that feeds near the bottom. Unless that tube is broken off you should have the near maximum available draw.
To remove the tank you need to remove the fuel neck. Removing this neck can be a REAL problem. The neck is held to the tank by a threaded collar (note picture). You need a spanner wrench (see picture), to remove it. Unfortunately, over time many of these necks have rusted to the tank which make their removal a challenge. Basically, you will need to place the nastiest penetrating fluid you can find over several days to convince the collar to cooperate. Good luck!
Tom