Mine was assembled in Milpitas with aluminium, still has it.

I've used steel, stainless, and aluminum over the years.  I like the durability of steel or stainless, but flare 3/8" stainless is impossible without a hydraulic flaring tool.  Trying to bend stainless into any kind of tight or complicated design is also almost impossible.  At 3/8" mild steel is also not a lot of fun.  Aluminum flares and bends easily.  My '67 has a pump to carb line I bent from aluminum.  I would definitely consider it for any custom applications. 

My 68 has all SS fuel lines but I would not hesitate to use aluminum as long it was not susceptible to stone damage under the car.
I used all aluminum fuel lines in  my home built exp plane with no issue. It vibrated a lot more than most car engines.
For me copper is not an option even though a lot of the antique vehicles used it, don’t ask me how I know!

I used 3/8 Cu-Ni. Flares easily.

The issue with copper is that it work hardens.  After installing, removing, and reinstalling a line a handful of times they tend to develop cracks in the flare.  However, copper can be heat annealed, so I wonder if that would prevent it.  I wouldn't use it on a vehicle that didn't have it originally, but for a 100 point restoration on an antique it might be worth knowing.

This same situation concerns me a bit with aluminum too though, because it is also known to work harden.  I believe the fuel line sold is noted as being annealed though, so hopefully that prevents it. 

I use all steel lines with the shortest amount of rubber hose where it is required for movement.

The new steel tubing, mine is 3/8” , is easy to bend and flares easily.  The only part I don’t like is the color.

Thanks for the input, looks like it is going to be the coated steel. Since most is under the car, no need for shine! And yes it is easy to work with and will outlast me. Once it gets to firewall I usually use the stainless braided hose under hood cause I always have it around for the racecar.