Seems you have a plan!! I agree that the 1070's are a good choice, if I was setting up a rig at this moment I think those would be my choice...
Have you checked thourougly the power consumption? I would feel better with a 1500W PSU... always better to have a bit more than risking a bit less...
get a pack of extra risers and don't forget these need to be powered risers...
Good luck and don't forget to send word about how everything is going...
cheers