I have had a number of fuel line leaks over the years. Some at rear where line jogs around a bit and then under the rubber in the clamps.
Took it to local garage seeing they have a hoist
They said they would use the new and modern nylon (or whatever the plastic is). They even showed me the special kit and tools they had for making the joints.
When they came to actually do the job, they decided to use steel lines. They kept the old front steel section which was in good shape. It has several bends. They connected to it with metal union connections at front. At rear, they used rubber hose double clamped. They replaced the complex shape at rear with mostly rubber hose, I think.
I noticed the lines now have surface rust, so I wiped them down and coated with Penetrol.
By the way, on my 72 R107, there are many rubber hose connections in the fuel system and it runs at 2bar pressure. But main runs are steel.