I wouldnt do that....all or none.On a carb'd car you could get away with it because of the lower pressure.You cant use hose clamp's for fuel hose connection's in these cars.
Youd have to weld a -AN fitting to the fuel line and thats not a good idea since it probably has fuel in it or has had it in there at 1 time ,read CAN AND WILL IGNITE.
I ran -10 to my fuel rail and -6 return.I had to mod the pickup on my new double pumper to accept the -AN line for feed and return.Its expensive though and alot of people will say $$$ better spent elsewhere...I say ive got a fuel system that will handle anything hp wise I want to put in a Regal body.I shouldve got a Weldon pump but plan's changed at the last minute.
Has anyone else ever noticed that the factory GM hanger has kink's in the tubing possibly hindering flow?I cut the tubing just behind the kink's so im pretty sure mine flow's more than a regular DP...