What's the right place to download the right dd-wrt for the R7000?

I have an R7000 and it's been great and all the articles pick it as a recommended router for dd-wrt. I've had dd-wrt on it for a couple of years now, and wanted to upgrade.

I couldn't find any clear ideas of which FW to use. I found this link:

http://www.desipro.de/ddwrt/K3-AC-Arm/

which has a file dd-wrt.K3_R7000.chk from Feb 2018. That's good but the existing dd-wrt installation seems to want a .bin file.

I logged in by ssh and tried to use ddup with the path to the .chk file and that didn't work.

I then did ddup --flash-latest

That did work, and it did it by downloading from:

http://www.desipro.de/ddwrt/K3-AC-Arm/TEST/

which I assume is the nightly build directory.

Everything worked, but do I want to be running nightly builds on this? Is there some more suitable download location for a stable build?

Thanks