How to cut the gas tank?

I am converting a 1988 Kawasaki Ninja to Electric and want to use the current gas tank, but need to cut the bottom out of it. I am not 100% sure the safest way to do this. One person told me to fill it with water and then do the cuts? Try to see if there are any other ways to get this done. I would like to cut out the bottom of the tank so that the sides and top all look the same.

Thanks for any ideas.

Philip

water sounds ok…

I know we drained ours, let it air out for 1-2 weeks, and cut it with a pneumatic air tool and cutting wheel.

so did you do it, if so what method did you use and how did it turn out

I have welded gas tanks by rinsing with water, (Filling and dumping a few times.) Leave the cap open and cut away. Use a small cut off wheel on a small cutter and follow your line.