As you have already noticed Sibwings Bird Dog doesn't include many liveries, just four, however there are a lot of interesting O-1 repaints all over the world.
It was our strategy, we were focused on mdls, different cockpits, eight pilots, weapons... And the repaints mission was left for army of repainters (btw, I'm a member of it, follow the text

http://sibwings.com/birddog/paintkit.zip - all-gray psd files
http://sibwings.com/birddog/paintkit_example.zip - ZK-NAM livery psd files
Remember that uv map is a bit different from model to model, so feel free to ask about any part location in textures.
As to repaints we are interested to collect them on our site, or at least links to them, so that people know they exist. So if you create anything that can be interesting to Bird Dog pilots please let us know.
Let's start
ZK-NAM
http://sibwings.com/birddog/repaints/zk-nam.zip MARINES on floats
http://www.sibwings.com/birddog/repaint ... arines.zip yellow RESCUE livery
http://www.sibwings.com/birddog/repaint ... rescue.zip USAF camouflage livery
http://www.sibwings.com/birddog/repaints/texture.pe.zip
Should I explain how to install repaints ?
Have fun flying Bird Dog!
Andrey