I've had to deal with rotten fuel lines on my '94 Nissan. Took me a year to find a suitable solution.
Like you, I was considering steel lines to replace the entire thing, but the steel lines I found were shorter than what I needed, so I needed to splice several lengths together. The issue I had was how to splice them together. The sections I could buy didn't have a connector on the ends, and the tools I could find for flaring and crimping were not inspiring my confidence, as they were:
- stretching the already thin metal in order to make the flared end
- the tool was leaving deep teeth marks in the already thin metal
- both ends were fitting rather clumsily and I could guarantee they would leak.
I spent most of that year looking for a proper tool that would do this to my satisfaction, did't find one. What I did find instead is a shop that sold all kinds of lines cut to your length with whatever connector you needed. Sure, they had steel lines, which are hard to bend without crimping. They also had some copper alloy you could bend with your bare hands and won't rust as quick as steel lines. $120 for all 3 fuel lines and they made them in about 10 minutes while I waited, complete with the ends I needed. Each line was one solid piece.
Of course, when I got in there to remove the original fuel lines, I got an eyeball on the brake lines and I got scared. Went back to the shop, $140, now I got both runs of brake lines for the rear brakes. Brand spanking new from the firewall to the rear struts.
Find a hose shop near you. Google for "brake lines," "hydraulic lines," that's the kind of shop you want. They make stuff for industrial applications mostly, but their tools and materials can handle automotive as well.