Update
Yesterday I received a shipment of most of the plumbing supplies I need. This includes -6AN fittings and braided stainless steel hoses. Tonight I assembled all the pipe thread joints using a thread sealant called Swak (made by Swagelok), which takes 24 hours to cure.
The under hood junction box and the cab control box are finished. The junction box has 6 connectors and the cab controller has 1. I have tested it and it works exactly as I planned. The remaining electrical work is making the cables that will connect the heaters, pump, ECM, batteries, and fuel pressure sender to the junction box. I'm trying to find a convenient wire covering for these cables. I used spiral wrap on the big 17-wire cable between the junction box and the cab controller, but I need something that'll work better with 2-wire cables (something small). I'm probably going to get some expandable fiberglass sleeving.
I'm using a Dakota Digital FP gauge, and I am rather impressed with the unit. I wired up a momentary pushbutton I can use to set the limits on the gauge (it blinks when the pressure is outside your preset range) and a toggle switch to dim the gauge at night if I want. It's very readable, and I am genuinely impressed with the apparent quality (and the price).
-Ryan