An older one is here:
http://wiki.freepbx.org/display/FOP/Installing+FreePBX+12+on+CentOS+6.5
If Oracle is more V6 than V7, you'll probably want that. But of course Oracle isn't going to add Maria, Oracle owns MySQL. So they're doing their best to block people from using Maria.
I'm not a big fan of Oracle, BTW. I can't even download the ISO (really. They want me to register, which I did years ago, and they'd then verify that I can download the ISO, which they never did. Even though I asked them repeatedly).
I'd recommend NOT using Oracle, and use CentOS 6 or 7, because it's a lot less likely to go crazy.