Not a 6.5 Creed but last fall I switched to 4451 from H4350 in my 260 w/ 120 NSB for whitetails. Without looking through my notes IIRC the charge was within .5 grain for the same velocity as the H4350. It also had a slight edge accuracy wise.
Here are both powders tested in a 284. http://bulletin.accurateshooter.com/...-new-imr-4451/

Bill