I replaced the fuel screen last year on my 81. I siphoned some of the filler neck and then just pulled the line and let the rest run into a can under the car. Amazing how much fuel was left. Be ready with something to plug that line and rehearse the move before opening the line. I got some fuel on the floor, but not much. Get extra cans ready to use, you may need them.
Screen is not had to change at all. Just threads in there.