The thought of wd40 and a bike chain in a steel can makes me cringe....no offense intended frotosride. Wd40 always leaves residue and ends up attracting dirt later on. There are better solvents...
...myself....I'd take the tanks to my local radiator shop....for about $50, they'll clean, pressure test, and repair the tanks as needed. Then I'd drive with piece of mind rather than replace x amount of fuel filters because I, personally didn't get the whole thing cleaned after a whole day and a half of supply getting, shaking, drying, wondering, forum posting, etc......only to find a possible leak later too. My personal MO....do it right the first time and save twice the time and money.