You should be fine flaring SS with a good quality flaring tool. It should be even easier if you only do a single flare. (probbly fine for fuel lines) A double flare (a must for brake lines) in 5/16 will take a good tool and a bit of practice.
Read the tech tips / instructions at Inline Tube.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-