Why do you want a parked or matte pistol? Looks? Ease of maintenance? Cheap to apply? "Tacticality?"
Personally I am no fan of parkerized pistols. The only pistols phosphate finishes look good on are the old war horses that have about 50 years of patina on them. It doesn't hold up to rust much better than matte bluing in my experience. And the solution will also roughen up every surface of every part, which will result in a grittier feeling gun, at least until the parts smooth out again.
To answer your question about grades of parkerizing, there are two main types: zinc phosphate and manganese phosphate. Zinc gives a lighter grey and manganese is a lot darker.
For a while I owned a Springfield Loaded that had a black phosphate finish that was nearly indistinguishable from matte blue, it was a little more "sparkly" if you examined it closely but otherwise it was a good enough looking gun.
Matte bluing is perfectly acceptable. Even if rust forms, it generally wipes right off with no damage. If you ever need it reblued, just have them throw it in the tank, and maybe a sandblast first if you are feeling generous.
I wouldn't even consider a paint or Black-T finish, but then again my SEAL days are behind me. And I think it probably is a mortal sin to put a park job or sandblast a previously high-polished blued 1911.
Here's a photo of my blued Sistema that was sandblasted with 100 grit al-ox first: