Alright, finally managed to crawl just above the freezing point today. The bracket I picked up was correct, but had absolutely no hardware, and the holes the coil screws go into were untapped, so I found some hardware that would work (stainless flat heads just barely worked) and tapped it with a metric tap at work. Went in and checked the plugs against the proper firing order. I'm more than a little confused how this weird mixup happened, but I labeled the plugs with the correct coil numbers. Threw on the Delco ICM and coils, trimmed the three coil screws closest to the engine because there was no hole on the engine mount for them, and she fired right up. The junkyard parts are good, at least. Went for a drive through town.... And the problem's still there. She sounds growly at around 1700 RPM and up still. I don't think it's a hole in the exhaust, because I should hear that even when idling. I'm gonna stop by my mechanic, at the very least he might be able to spot something under the hood (no helpers to rev the engine for me sadly, and I don't want to grab a brick).