I've used thick walled rubber heater hose on mine . They also have braided reinforcement in the rubber which is pretty standard. Standing/looking over the front bumper they run from the top of the engine, across the top of the bulkhead, down the LHS corner of the engine compartment and alongside the sill where they join the good bits of pipe left. Where they come off the engine I've used 2 taps, those with balls in, so you can turn the heater off in the summer. Some of the LC heating system incorporates rubber hose so I can't see how this method would be inferior. It will certainly last longer than those steel ones.
Frank