I hope to shout that a grease gun hose would hold up. They're only rated for about 1000 psi.
Your hydraulic shop could fix you up with some push-loc hose and fittings and you could make them any length you want. That hose is rated for at least 100 psi. I just replaced all my fuel line hoses on a 7.3L and it cost me all of $17 for about 6 feet of hose. I already had the fittings and reused them. You'd need 4 fittings and a few feet of hose. Not going to break the bank. JMHO.
If using rigid brake/fuel line be sure to put vibration loops in them. Unless your filter is mounted on the engine. Mine will go on the inner fender above the steering gear.
Was never worried about the pressure of the grease gun hose. The thing that’s always been in the back of my mind is heat. Hard to find any sort of heat rating on them. That, and the fact they are all made from pure Chinesium nowadays.
