Back to stock

Where can I find stock XT1096 5.1 signed images? I have my bootloader unlocked and I'd like to essentially factory reset my device. I still need/want the bootloader unlocked and I want the ability to root and everything. I just wanted to experiment with android pay and see what is causing it not to work at the moment.

What is the best course of action to start fresh? I'm familiar with flashing images on nexus devices if that is an option.