These lines since new have been set-up as rubber I am guessing a hard line may be subject to vibration and an eventual failure? Why don't you like the rubber hose versions? Most vendors carry them if you don't care for NAPA's.
https://www.flickr.com/photos/advance-design_parts_co/15652083208/in/set-72157631868452754

1950 Chevrolet 3/4-Ton 3600
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