I run similar setups on a Apex mini Quad with a CR85 engine. Shark fin for the brake Rotor. and a one sided Sprocket guard. I would run a single sided sprocket guard and DB chain guide, just like on the apex. I do not like the dual guard on the sprocket Ive seen a lot of broken cases from chains jumping onto the inner ones also mud builds up in them when there dual sided.
As far as weight being an issue, are you Drag racing all day or riding, this apex races through the woods and water for a hour at shot and you cant feel a difference.