I'm fairly certain the excess heat from the unwrapped header + the lack of a heat shield was causing my battery to struggle to crank the car when warm. I had a DME heat shield that came with the car, so I put that in place but have not driven enough to see if it has had any positive effect.
While I sort through the charging issues, I contacted Rotora and got a drawing of the brake pad so I can get some pads made for the car. The caliper is their FC4 caliper and it is paired to a 330x30 mm rotor (need to verify rotor dimensions, but this is what I suspect..). I couldn't find this info anywhere on the interwebs, so the pad is roughly the same shape as FMSI D810. The Rotora pad is a few mm shorter, has clearance for dowels/pins, and ~3mm thinner than the D810 shape. Needless to say, I called Porterfield and they were able to immediately start on a set of Raybestos ST45 pads. I also picked up a set for the stock rear calipers.
More on the
tail light issue: the driver's side
tail light running light is dim, the passenger side is too bright. When I unplug the driver's side, the passenger side looks normal. When I unplug the passenger side, the driver's side doesn't work at all. If I switch the lights, the lights work the same regardless of position. I also snagged a cheap AP2 driver's side light and plugged it in, nothing changed.
I checked and I have 12v at both running light pins with the wiring unplugged. I'm going to check voltage at those same pins with the lights connected and see what I get. This is the definition of an AP1>AP2 tail conversion gone wrong, lol.