John added many commits to the normal cm12.1 kernel, that is why his defconfig does not work.

I would stay with stock cm12.1 kernel and see if everything works in Sailfish, because you do not know what and why John added some commits and maybe they are not necessary anymore...

But if you want to try his kernel, kernel download is only around 300MB

Just go through the list of mer kernel check and make the changes to your defconfig.
The necessary options can be found here: https://github.com/mer-hybris/mer-ke...el_config#L196