For my 351-W with nitrous, I ran a hollwy blue from the sump in my tank. Spilt the 1/2" aluminum line with a "Y"-block. One regulator for the Holley 780 and one for the Nitrous solenoid.
p.s. Still have a (really beat up) Autometer 2-5/8" fuel pressure gauge and Y-block splitter and some 1/2" blue anodized fuel line for sale...
See my Zephyr photos:
http://www.dariusrudis.com/mustang/zephyr/