Need help on AN conversion

Hey guys, quick question here about AN conversions.
I am trying to order all the fittings and lines for my new fuel system and am on my last obsticale.

I need to find out what size adaptor I need to order so that I can fit -8AN 90 degree elbow into this Mr. Gasket carb Inlet line. http://store.prestoliteperformance.com/chrome-fuel-line-kit-w-gauge-fittings-1404.html

The site says it has "Inverted flare female inlet thread size 5/8-18."

If you can clue me in on what part I need I would really apreciate it!

FWIW: The system will be a new tank, 3/8" sending unit, -8AN braided line all the way to a new Edelbrock Mechanical pump 110 GPH (6psi), then 90 degree elbow to a russel filter to more -8AN line, to a 90 degree elbow, then into the adaptor Im asking about. Thanks guys!