John,
Have you considered replacing the Porsche fuel line with AN and using adaptor fittings? I did such a thing in my old 3.2. Earl's sells a bunch of AN to metric adaptor fittings. It probalby wouldn't go with your theme, though of complete OEM parts.
Also, I worked well with Len from
www.Autosportengineering.com in Mass. He's a Porsche guy and has run a shop for 30 years. Len has metric swaging dies and buys bulk German hoses and fabs up replacement lines for various applications I used him for my fuel line in the 3.6 conversion (I have the factory 993 rails and hoses), but also some soft oil lines.
You might contact him to see if he can help?
Good luck,
Doug