Nice image, Erik! I had a go at 6744 a couple of years ago and as Mike said, it is a tricky one.
eXcalibrator (
http://bf-astro.com/excalibrator/excalibrator.htm) might be worth looking at if you want a semi scientific (well, it does involve fudge factors) way to figure out the colour balance.
Cheers,
Rick.