I could be mistaken but you may be looking at this wrong. When I did this with the Hall lines 10 years ago I reused the fitting that screws into the caliper. It threads off of the rubber hose. I had them apart a year ago when I rebuilt my calipers and nickel plated those fittings at that time. The fitting you show in the picture I used on the other end to go through the fender and couple the hard line. I believe there were nuts that fit the thread on those bulkhead fittings. I can take pictures tomorrow if necessary.
Steve