So I created a build for this system a few months ago, I was using the DanCases A4-SFX V2 for that with a GTX 1080 FE and an i5 8400.
Since then I have changed it up a bit, the only carry over parts are the Motherboard and the SSD, but everything else has seen an upgrade.
The biggest points for me in this revision were: 1. GTX 1080ti FTW3 - This is the biggest GPU that will fit in this case and if you've seen it in one before you know that it's a sight to behold. Also I managed to pick one up cheap just after the RTX launch. 2. Alpenföhn Black Ridge - This is a cooler specifically designed for the Dan and is the only cooler I know of that supports a 120mm fan that allows me to have a quieter system. 3. i7 8700T 35W CPU - I really wanted additional cores and threads with lower temps for a silent system. For this the 8700T is the best option. I could only get an Engineering Sample from TaoBao which was actually very affordable and with some VLP ADATA RAM, allows me to run a slim 120mm fan with the Black Ridge. 4. Ensourced custom cables - I had some Ensourced shorty's with some Cablemod extensions on the last build which looked great, but were not flexible and were too long. Ensourced has an amazing editor and heaps of options which allowed my to create some awesome cables which are the right length and easy to route.
With all that I think I have, what is in my opinion, a pretty close to perfect SFF system. I could put a 2080ti and a 9900K in it, but that would be hard to cool and too expensive for any kind of performance gain, so it ultimately would not be worth it.
I will add additional images of the cooler and mounting process shortly, but they are on my main camera and these photos were taken with my phone.
Let me know if you have any questions about the build.