Messing with the gas tank is always sketchy for me. I heard a story recently about a guy working on his F1 gas tank and he burned his shop to the ground. The vapors got to the electric heater he was using in his shop. Fortunately he was not injured severely, only minor burns.
Take care when draining it and capture the fuel in a spare fuel container to protect from an ignition source. It’s not uncommon when I work on the truck on a creeper to get a static charge when I touch the frame or a running board, which is why I am extremely careful when a fuel source or fuel vapor source is present.
JB