I've done a couple Painless systems, one NW Autowire system, and one EZ Wire system. None of them on a Camaro though. The Painless and eZ systems I used were on Chevy cars, and were very user friendly, but did have less than perfect instructions. I found a lot of wires double marked for the same devices, and was puzzled by it. Eventually I cut all the wire ties on the bundles to each area and realised there were jumpers tied into the system to hook various items like gauge lights or power.
It's much easier if you lay out the various harnesses and remove all the wire ties except the first couple at the fuse block. Then you can remove excess wires. You'll also find that Painless and EZ both give you lots of extra length to reach the rear tail panel and I had excess wiring that had to be dealt with in back. It can be shortened and spliced, or carefully coiled and hidden where it wont show.
I used a NW Autowire Universal 12 ckt. on my gasser, and I found it was the easiest, but probably wont work on a Camaro. It didn't have a connector to plug in the steering column, but I didn't need one. It also came with just enough wire to reach about 5' from the fuse block, so I made up front and rear harnesses to connect under the dash.
Making up all my own harnesses, and starting with an empty shell and no wires was easier. I prewired all my gauges, and then prewired all my tailights, fuel pump, and fuel sender, then ran it ll to the dash. Did the same with the headlights, front signals, engine wiring, and ran it all to the dash. Then it was just lots of splicing and heat shrink to terminate.
Took me about two days on each system to wire them, and then a half day to clean and dress down the harnesses to get it all neat.