So you want someone else to come up with the story and setting? Why is is time period of interest too you?
Also, those Natives in the picture are likely Apache or Navajo from the later 19th century. The Natives involved in the Seven Years War were living on the other side of the country, they were completely different tribes and there's over a century difference in the time period. That's like asking to do a Vietnam War RP and showing a picture of Napoleon's soldiers.
Lastly, the GMing issue is something i can't do much about. All I can hope for is that someone with enough experience would be interested in this as much as I am.
Uhhh the history nerd in me is freaking out for this one and a great place for things to kick off would be the Battle of the Monongahela. But if I was to play I'd probably want to play as French irregular.