if it's an NOS kit, the nitrous reg is the blue round looking thing , that is not a selonoid.
is there a kit on it? just look at the nos instructions for that...find it on
http://www.holley.com and follow the links to NOS
the fuel press reg is behind the upper intake, 3 screws, then swap it out , there is a red(probably a red) vac line on the top of the fp reg.
and are you talking about the regs? or guages? just to make sure....