I don't think those "fire stops" do stink for structural integrity. What is preventing the wall from racking now? That blackjack? Is the blackjack as tough as plywood? If not, I'd remove it, remove the fire stops, and plywood it. OSB is not good if it ever gets wet. I guess that would mean tearing off the siding, too, but then you'd have a nice wall. Do it in small sections, of course.