growing out dilema

I would be so very appreciative of some professional advice here is my problem:  My hair is naturally dark ash blonde 50% gray, I am wanting to grow this natural color out I have one inch of regrowth. The rest of my hair which is shoulder lenght is a warm blonde, it is not intentionally warm it just always comes out that way. Here is what I have been using.  Miss Clariol gray busters in 89N level 9/base neutral mixed with Miss Clariol 12 B1 blondest beige level 10/base violet. 30 developer. I would like to make my hair as close to my root color as possible, in order for it to grow out.  What should I use? Do I need a filler if  I use perm color? Would I be better off using a temp color like redken shades EQ? I am a nail tech so I am able to purchase professional products at the beauty supply. PLease tell me what the best way to go is. Thank you