Check the mastheads for the appropriate editors. Most publications have features editors.

Don't know your publishing background, but you need some pretty strong clips for most print national print magazines. Without those, you may find it hard to break into these kinds of pubs. An alternative that may be more receptive are their online versions. I'd suggest pitching one of these if you strike out with the print pubs. They pay less but your chances of getting the green light are enhanced.

Also, 10K is really long. If you aren't Susan Orlean or Malcom Gladwell, you don't stand much chance of an assignment at this length from your target pubs. My editors usually set the length dependent on what they need. (I know some advise to include proposed story length, but the higher you move up the freelance food chain, you'll find that's not necessary,)