I think with proper undervolting the 7700K will be okay. You can even overclock it a tiny bit, to 4.6GHz on all cores if you have a good chip. That is, if you won't be running it at 100% for long periods of time, then it'll get hot and loud. For gaming you should be fine, games don't run the CPU at 100%, most games don't get anywhere near that. Even Noctua clears the L9i for 95W chips and they are usually pretty conservative. I think this case counts as having good ventilation because it's basically all fresh air intake and immediate passive exhaust, there's really not much case to speak of, it's a mesh box. Again, with undervolting, and even a small overclock, I think you can stay south of 95W, and you will certainly be okay with no overclocking.
Remember, you can always underclock the 7700K to perform/consume the same as a 7700. And considering it costs about the same as a 7700, and you will be getting an aftermarket cooler anyway, and it will have a much better resale value, I think it's definitely worth getting a 7700K.