What wrenches do you have sitting in your tool box right now ?
Put the open end up to the bolts and match it up. You will not be able to get a flare nut wrench onto the portion welded to the filter based upon your picture, showing the retainer bracket for the outgoing fuel line. If you dismount the gauge, you can use a flare nut wrench for the top brass fitting to the fuel filter, but more than likely an open ended wrench will work, or a socket/ratchet setup. Sizes are large on the filter, somewhere 21-22 MM, but I could be off there. Most filters this style are close to that.
Somebody here will know the size, off the top of their head. Lots of rebuilding going ahead as the winter wears on. Oh, and whatever you re-use, don't reuse the copper crush washers, always replace those.