You said you've replaced both filters. Where is the other one? I run two clear filters - one ahead of the pump in place of the tank selector valve and one between the pump and the carb. The first one protects the pump, and on trucks that have sat quite a bit usually has to be changed frequently as it catches a lot of rusty silt.

If you need to replace the hose on top of the tank, and I'd bet you will, there is usually enough length on the bolts holding the tank on via the straps to let you get to the hose w/o taking the tank out. And, make sure that all of your connections are tight as any leak ahead of the pump kills it's ability to pump.

If the hoses don't seem bad it may be the pump. Chris is right on with his suggestion to check pressure and volume, and from what you've said it does sound like a fuel problem.