First ported Android 4.4 KitKat ROMs are already available for the Nexus 4 and Nexus 7 (2013)
The ROM was ported by the critically acclaimed team behind the ParanoidAndroid custom ROM, and it really is as close to stock as it gets. Do keep in mind that it doesn't include in it things like the new Google Experience Launcher, so you'll have to sideload that one, including the Google Apps package. Of course, that is if you're actually willing to take on this risk, seeing as the Nexus line is usually pretty fast to get the next updates. Oh well, some people just ain't good with patience, so to you we say to tread carefully – if you mess up your devices, you'll be the only one to blame. You've been warned.
You can download ParanoidAndroid's Android 4.4 KitKat port for the Nexus 4 here, and for the Wi-Fi only Nexus 7 (2013) here. You'll be needing them Google apps, these are downloadable from here. Happy flashing y'all!