I think the important thing is:
1. You are interested.
2. There is more than one Greek Organization out there to look at.
3. Contact someone from a Soroity and introduce your self to them. Explain why you did not join in undergraduate years and why you are wanting to do it now.
I dont feel color should be that worriesome to you as you can see on GC. Bounderys are being crossed alll of the time.
Sure there may be some that still do, but the majority dont!
Just remember, "the dumbest question is the one you do not ask!"
Good Luck and keep us posted! Shame Jill is not near you, you would have a ball! One Neato Lady and AP!