I have about 6 inches of headspace before the start of the neck, of my carboy.....is this two much???
Did you go from a 6.5gal bucket/carboy to a 5gal carboy? If you did, you should be fine. That is the reason I brew 5.5gal batches, so that I can rack 5gal of clean beer into a keg or conditioning carboy.
Yes, my primary was a 6.5 gallon bucket (was in there for 2 weeks)
There's no need to worry about the air space. Any CO2 offgassing will fill the gap and push the air out.