http://mirror.centos.org/altarch/7/isos/armhfp/
There is a raspberry 3 image but 32bit only for now...64 bit cooming soon...
https://wiki.centos.org/SpecialInterestGroup/AltArch/Arm32/RaspberryPi3
Epel 7 repo from redsleeve:
http://ftp.redsleeve.org/pub/el7-devel/el7/EPEL-full/mirrors
i'm tryng this... the pi with little overclock @ 1.3ghz with samba, transmission, fail2ban and owncloud 9 works very well 