How far did you drive it without the cam seal in!!? They don't fire oil out under main gallery pressure.
Megane pistons are still liable to cracking ring lands, even more so if different fuel has been used to when it was mapped. Do it right do it once imo. Forged build or not atall.
I'm not sure, not far as I only went to Tesco's and back, 4 miles there and 4 miles back, car started juddering/missing when I was nearly home, pulled over seen the oil everywhere and got towed home.