Perhaps what you're looking for is "MediaTek Ralink MIPS", followed by "MT7621 based boards"?
This combination can build profiles such as "D-Link DIR-860L B1" and "Firefly FireWRT", which closely resemble the architecture tags shown by the various image file names in the Oolite V8 building guide.
If you want to use this target/subtarget as a starting point for adding a new profile, then what you'd do is modify the ./target/linux/ramips/image/mt7621.mk file. That's where you'd add a new profile for Oolite 8.0 board. You could review the source files provided by the Oolite project to determine what settings they use for their custom profile, and what DTS files you'd need to copy over to the ../dts folder.
All in all, I would download the Oolite source code to a new directory, and then run a directory diff between the two ./target/linux/ramips/ folders. This should give you an overview of the differences.
This is quite normal. In the LEDE trunk, the subtarget-specific configurations were migrated over to their own 'mk' files in the image subdirectory. These files are then included into the "main" Makefile depending on what subtarget is selected.
You do not see the same in the Oolite source code, because it is based on OpenWrt 15.05 which, in turn, has not experienced such re-arrangement.
Because of this, I am somewhat sure that the way you copied the profiles over doesn't work as expected. This may manifest as compilation errors even when there should not be any.