Re: 1956 7.5 sea horse shift issue
They should. The line isn't special aside from getting normal fuel line of the proper size. Although, you may want to consider converting the motor to a modern, single line set up with a fuel pump. It's a pretty quick, easy and relatively cheap ($70 or less) job you can do yourself. A lot of folks here do it so they can simplify there system and don't have to worry about using the pressure tank. If you're interested, there are tons of threads that can walk you through it and I can give you lots of pics/vids to guys doing the job on youtube.
P.S.
NAPA also sells Sierra brand OMC replacement parts (points, condensers, carb kits, impellers, etc....). If they don't have a particular part in stock they can have it delivered from their warehouse by the next day for FREE! It's like getting free overnight shipping.