no working PoS coin p2pools at all afaik
http://p2pool.novaco.in/Current version: 11.4.1-1-g8ab0349-dirty
Pool hash rate: 61.186Mh/s (5.51% DOA+orphan) on 32 peers
If you wish to perform adaptation of p2pool for any cryptocurrency, then there is absolutely no problem. And PoS doesn't create any problem here.