1982 Chevrolet 2500 - How to clean fuel cell

So I have a 98 gallon fuel cell that was used as diesel cell but I want to use it for gasoline how would I clean it out? I’m going to run it in 82 Chevy with a 454 engine

As long as you have drained all the diesel out, I wouldn’t worry about it.

a 1/4 gallon or so of diesel mixed in with 98 gallons of gasoline is not going to be noticeable.

The 800 lbs. of tank and fuel will be noticeable though.