So, I think this makes it a 45 degree double flare fitting for 5/8" OD hard tube. Correct?
Totally incorrect. That takes a male inverted flare fitting that's already on a piece of 1/2" OD steel fuel line (two of 'em, actually) that can be bought in a variety of lengths at any local parts store. Buy a piece of hard line, cut and bend it to fit, and join it to your remote oil filter adapter with 1/2" compression fittings. Problem solved! What's the obsession with AN fittings? If you want flex lines for some reason, have your hydraulic shop put 1/2" inverted flare male fittings on a piece of single braid line. problem solved again!
Jerry