Very nice! Did it seem scary to you, inducing rust on a gun instead of working to prevent it? First time I did it I was in a mild state of panic the entire time.
Astonishing what a nice bluing job can do for an older (non-minty) gun! Thinking I want to do that with my CZ 70 now! 
Do it and post pics!
Forgive the noob question, but is it necessary to remove the old bluing first?
Do you have a link to the product you used for this? Thanks!
Yes. Rule of thumb, anytime you refinish anything, surface prep is always one of, if not the most important steps. If the surface isn't uniform, the refinish won't be uniform.
Birchwood Casey has a blue remover, main active ingredient is phosphoric acid. You probably won't drink sodas again for a while afterwards, it smells a little like old, flat, stale Coca-Cola. Then you realize the ingredient that's eating off the old finish is also a Coke ingredient going into your stomach...
What I found to be the easiest for me was to find a machine shop, or powder coating/welding/automotive shop with a blasting cabinet, then pay to have it bead blasted. Removes the old finish and leaves a uniform matte texture in it's place, which was easier for me to blacken. Most it ever cost me was $40. In my opinion, well worth the time and energy it saved me.
