I JUST FINISHED installing ISSPRO gauges on the pillar in my 96. I bought the kit from Diesel Manor. They assemble everything and include extra wiring and connectors and their own set of instructions which are more accurate and complete so you don't need to go through the individual guage instructions. Perhaps Geno's does this as well.
It was a little difficult to fit the 4-wire connectors behind the pillar where the wiring connected to the gauges, but I did get it done. I believe this is part of the preassembly that Diesel Manor does; there are probably some better ways.
I put in the Boost, Pyro, and transmission gauges. I have the AST exhaust manifold to still install, so that probe's not in yet, and I'm ordering a new transmission tank, so that probe isn't in yet either.
I didn't bother to paint it, just left the pillar black, so I can't comment on how well it holds the paint.
BTW, It took me a while to figure out that I keep the factory pillar piece, too, and the new one goes on top of it, so don't break it taking it out. It snaps free pretty easily, though.
The factory service manual was invaluable for learning how to remove the dash trim to access behind the headlight switch for the dimmer wire. It's the smallest of the wires there, but verify everything with a test light.
I found the best place to access the 12V ignition "ON" wire was just as it entered the fuse box from the back side. I took the prefused wire and then immediately added the inline fuse included with the kit.