I've spent many a year plumbing with flared and compression fittings, and also put SS brake lines on the WRX.
Either get yourself (if you are confident of ability) some SS fittings and cut that flair off. You will need a pipe flaring tool (try plumbing section of Home Depot) that can flare 1/8" (not sure about size, measure to be 100% sure) pipe, a SS compresion coupler to couple your old brake lines to the new section you are about to make, and a new SS flare nut. To be safe, use 1-2 wraps of teflon tape on the compresion ferrels of the coupler. Carefully bend (use a mandrel if you can find one at home depot) in the new section and MAKE SURE YOU PUT THE NEW NUT ON BEFORE YOU FLARE THE PIPE. Do not over tighten the nuts. You should only use a 4-6" crescent wrench. Once it's all completed, tell yourself "I'm the man" and check your work for leaks. As always, test brake work on empty roads.