As I recall, the 300E has a fuel cooler built into the manifold assy. The expense of this hose was the reason we invested in equpment to build those hoses.
The techniques are common but don't use a hydraulic shop unless they are specifically set up to do A/C hoses. I would check with your local MB independent or with a high volume A/C only specialist.
The process will involve cutting the swedged fittings and rubber hose sections from the formed metal sections. New barbed fittings are then welded/brazed to the formed metal pieces and new barrier hose crimped to the new fittings.
Bosch Master, ASE Master, L1
33 years MB technician