Bought some stuff: Iron Canyon Motorsports fuel sending unit (converts resistance-based senders to a 0-5 V signal), Speedometer Solutions digital speedometer converter (Hall Effect sensor that screws onto the stock transmission take-off), and a pair of Sakebomb Garage IGN-1A mounts.
I've been trying to get back into working on the car. So far I've only manage to take apart more stuff (side mirrors, window trim, wipers, etc.) and work on the fuel tank cover. I decided to keep the current cover so to combat the rust I soaked it in Evapo-Rust and gave it the POR-15 treatment. As with before I cut out the stock fuel lines and drilled holes for the AN fittings. I don't remember everything being this cramped on the S5 cover. This is basically as it sits now:
The through-cover electrical connections are different on the S4 so I had to come up with a new plan. After drilling through some sealant-type stuff I discovered the exterior connections are essentially ring terminals. Instead of being secured with a nut they're crimped onto a top post. The post is very close in diameter to a #10 bolt so I took a #10 ring terminal, soldered it to the post, and filled the rest of the "boss" with epoxy.
It's not pretty. Hopefully the epoxy will keep the contact from corroding and/or failing. A quick continuity check showed no voltage drop to the nearest .01 V across the post and ~24 in. of wire.