there are a million diffent things that you can do. if i was you i would go with a b-16 head, wiseco pistons (with a high c/r), rods of some sort, cams, intake, ehxhaust, etc. this will easily be a fourteen second car.
p.s the reason that i suggest rods is because ls motors are not engineered to be 8000 rpm motors if you rev that high with as long of a stroke as your motor has, your piston speed will be crazy high. the weak link in this formula is the conection point between the rod and piston. if all of this is stong then you can over come the added stress of all of those extra revs.