When you pull your fuel tank, be sure to remove it from the area your welding in. It is truly amazing how far a welding spark can travel on the ground.
Remember it’s the fumes that create a high percentage of explosions.
And why your tank is out do not miss a perfect opportunity to clean the scale/crud out of your tank.
I have a 79’ K-30 w/dual tanks. The first thing on my list is to pull both tanks, clean them out & replace all rubber components.
YouTube has a few blurbs on ways in which to accomplish this task 