A few suggestions please

Hi:

I am a long-time lurker on these hair color boards and I am learning a lot.  I think that I am about a 4 ash natural with some gray around the temples and forhead.  I would like a few suggestions.  I have been coloring my hair with both perm and semi-perm colors for a long time now.  Right now I am a dark brown color, kind of like this

Sort of a Irish-Setter dark brown with red tone to it.  It is ok, livable, but not what I really want.   I really want this.

But, I don't know how.  I have so many tests patches in my hair now that I am turning them into highlights and I have only reached this color with bleach and Redkens EQ 6N (dark ash blonde).  

I did try Colorfix (the shampoo formula) to try and lift the base color a little and that's when I got the Irish Setter look. 

Here is what I thought I could do.  I will Colorfix (full strength) whole head and then tone the orangeish with Redken EQ 6n, which is described as a dark ash blonde.  I liked this on my highlighted strip (which was bleached first).  It was perfect for a highlight but too light for my base color. 

Now, what do I do with the regrowth?  Do I just use a permanent 6A with a 30 developer to lift the virgin 4 ash on the regrowth?   Sort of confused at this point. 

Sorry for the book, but I would appreciate any suggestions. 

Thanks