I went through the same process in 1991, when I wanted to replace the OEM lines with braided stainlesss lines on my '81 with dual front discs .
I tried 4 times to get the correct set,ended up going to an aftermarket BMW parts supplier, Luftmeister while I was on vacation in southern California, took the lines in had them made up right then in about 30 minutes .
I just replaced the lines on my '84 LS and I don't think the LS upper line from the master cylinder to the splitter will work on an '81 .
If you don't get any satisfaction with Galfer, the last set of lines I bought, was from Spiegler Performance .
They manufacture their own lines in house .
My suggestion if all else fails, is to send them your lines, and they will copy them, average turn around time is about 2 weeks .
http://www.spieglerusa.com/They also rebuild OEM BMW rotors into semi floating rotors, if yours are worn out .