BCC boas are the "true red tails" such as Peruvians, Guyanas, Surinames, etc

BCI boas are Colombians, Central American types, Hog Islands, and other Mexican and dwarf boas, etc

BCCs will get larger than the BCIs, though some Colombian females can get up there in size.

You also have BCA, BCOs, and BCLs but I recommend a BCI for a boa beginner.

I would look into a Colombian male, as males usually get smaller than the girls and I don't think I've seen a male BCI in the 9' range personally. My male jungle is about 6' right now and manageable. You've probably seen anery and sunglow Colombians though Central Americans can come in those morphs too.

Male Colombians will need at least a 4' long cage, with females and extra big males needing a 6'

Rio Bravo has wonderful info on all things boa: http://www.riobravoreptiles.com/index.htm