Eh. Why not use Immolation? I would expect a Fire rush deck to pack in some of them. And Deflagrations do nothing to help the rush.
Thus, this is what I suggest.
Replace 4 X Deflagration, 2 X Fire Bolt, and 6 X Fire Pillar for 6 X Immolation and 6 X Spark.
I know, I know; Spark isn't a fire creature. But whatever.