I believe the '3 leaves' are stylized feathers representing the Prince of Wales. They will appear on the tang, some of the brass furnishings, in this example on the Ketland lock, and will appear in a more primitive form as the front final of the trigger guard also as seen here. Photos of the side plate, front sight from above and the ramrod out of it's channel would be nice, however everything shown suggests those too will be right. A cool trade gun, early and maybe out of eastern Canada!! Iroquois???