dunno if can help/inspire, but here's Nougat sources for MSM8916 devices:
(note: at VF-895N - a device based on same chipset - community are working on CM13 too, a collaboration may could help both: http://www.htcmania.com/showthread.php?t=1255937 )
Nougat for elephone trunk is already here: if you're eager to try it, you can use Mokee for Ark Peach. I have also tried to compile the sources with the small changes (partitions sizes) needed for the trunk: it works. It's only 32 bits, though, and I have tried it only for a few minutes.