More than likely. I am running a 6700k & 1080 mini in my S4M but without the Dell 330w and instead using the HDP 400 AC-DC as a "power brick".
Provided you don't over clock too much, or better yet undervolt the 8700k and keep an eye on the 1080 power consumption. Should be fine. Look around on SFF. I believe I've seen multiple ppl doing the same thing as yourself.