I'd like to recommend one of two products I've used with great success in loosening rusted fasteners: "Kroil" by KANO LABORATORIES, and "SP-100" by PROLONG. I've found the first at supply houses servicing industrial accounts and the second at NAPA. Soak'em overnight. Begin the next day by TIGHTENING them just a few turns and hitting the threads above and below the fastener with a wire brush. Once it seems to begin to move, I'd apply a little chassis grease to the threads so that it'll work its way into the fastener as you loosen it the rest of the way. Don't cut the retaining strap(s) unless rusted through, as they'll clean-up pretty well. I'd make that decision based on whether the strap edges have rusted "inwards" towards the center by one eighth the distance to strap center. I like to use a wire wheel at low rpm to see if the metal isn't all the way gone, but, if need be someone could probably make some new, (I'd try for a SW US salvage yard pair to be sure of fit). (Believe YEAR ONE or other has this peculiar fastener; maybe even MOPAR). As to the pickup being clogged, (replacements for this "sock" filter include the above), I'd try cleaning it as much as possible and experimenting to see if it will work. Otherwise, there are rebuild services I've seen advertised, @$120.00 or so. Also a good idea to have the tank refurbished, as, the system needs attention all-at-one-time, not piecemeal. I would also expect the fuel lines going forward to be a problem, that is to say: there is no way I'd put a refurbished tank/pickup back on without replacing the lines to the fuel pump and carburetor. INLINE TUBE and others keep the patterns available, both in OEM steel and stainless; prebent, with armor and clips as per factory. Replace all soft lines with EFI-rated hose and use stainless steel worm drive clamps; (all available from NAPA). Don't forget the vent line (hard and soft pieces) at the tank forward end. Consider that the fuel pump is also best replaced with an equivalent CARTER piece and I'd give the carb a minor overhaul as well (gaskets, passages clean; leave choke well enough alone). I realize that this is an awful lot of advice, but fuel problems are often not easy to diagnose, one tends to think of ignition problems, etc, and it becomes frustratingly confusing. On the other hand, if one knows the fuel system is functionally "new" this alleviates more than one potential headache. Remember that no modern EFI system would EVER continue to function with the problems on top of problems your system currently has, and, once made new (and kept to a minimum maintenance standard; i.e., have a drain plug installed in the tank; drain annually; use gasoline preservatives during periods of inactivity [best is a couple gallons of VP Racing Fuel ]), will remain that way another quarter-century plus. Good luck