Brake line fitting, if not 1/2 or 9/16th?

[b5blue]

  Doing new lines with my disk brake swap  I got all new lines from "Fine Lines". Trying to tighten the new flare nuts to the rebuilt 73 manual disk master cylinder's used connections was problematic. Tighter and tighter still weeping a slight amount of brake fluid. Loosening then re-tightening a bit more was recommended on several places online to mate the new tube double flair to the existing used fitting so I tried that several times.
 That's when I noticed some "slop" in the fit of my 9/16th line wrench on the fitting to the front brakes flare nut at the master. The rear brake flare nut fit snug on the wrench unlike the rear? 1/2" didn't fit at all so I pressed on until the nut was so tight I overran the flats and the nut deformed binding to the wrench. 120.00 and 10 days later with 2 new lines and a new master to install I started checking fitments. Clearly the dang master to the front line nut must be 14mm as nothing else is even close...wtf?
 So now I'm off to buy a 14 mm metric line wrench for one single fitting on my 70 Charger. I'm a bit confused on the entire thing and moving on hoping for the best on the 3rd redo of what was just to be the simple Disc-o-Tech brake swap.  
I'm just posting this as a heads up as nowhere does anyone even mention this slight detail. The line set I ordered is all standard 70 Charger drum parts and the masters are Mopar stuff, nothing custom.  
 

[b5blue]

Just to be clear on a master cylinder the front brakes are fed by the line on the master that's closest to the firewall.