Well, I've done some digging, and this is what I've found.
There's a good treatise on brake lines here:
I'm not going back to plain steel brake line, so the basic stuff at Autozone, etc. is out. That link refers to Bundy line and Kuniper line as options. These options appear to be better than "just" steel replacements, with the Kuniper being the best choice. I was wondering why my VWs and Volvos have never had hard brake line issues, and it seems that Volvo has used the Copper/Nickel alloy Kuniper lines since 1976 in their vehicles. The Bundy line is steel, but it is treated/plated for corrosion resistance.
BUT, I can't wait for Kuniper line to come it, I need to get the brakes done this weekend so we can go camping next week! I'm going to go with Bundyline. This is available from McMaster-Carr, and there is one near me where I can pick it up Will Call.
Another option is pre-formed Stainless Steel lines from http://www.egrbrakes.com/index-main.htm
. They quoted $350 for the hardlines, and $200 for Kevlar/SS flex lines. Again, I can't wait the time for these to come in, but this also looked to be a good solution. I'll probably do their upgrade for the flex lines at some point, at least.
So, for someone facing replacement of their rusted, original steel brake lines, the Bundyweld tubing line is available as shown here:
and the Kuniper (Kupfer-Nickel or Copper Nickel) is here:
or there is the SS upgrade mentioned above.
I hope this helps the next person who searches the forums after finding an empty brake fluid reservoir and a puddle under their Ram