If a meat roaster rack has become contaminated with mold, etc, would soaking it in hot water and bleach (0.5 cup bleach to 1 gal of hot water) for 2 - 1 hour cycles with hard scrubbing between soaks the baking in the oven at 450°F for 1 hour be sufficient to kill any toxins that may be present?
You don't have to go crazy, you just need to get all the grease and accumulated gunk off of it to make it safe to use. Bleach won't help you get it clean, it will only sterilize, and then only if the water itself is clean - there's no point putting chlorine in dirty water. If you want something to help you get it clean a heavy duty kitchen cleaner or something like simple green is what you are looking for, although lots of liquid dish soap and a scourer will probably do just fine. If you get it good and clean you won't need to use chlorine or bake it because you'll have removed anything potentially harmful, but if once you clean it you still want extra assurance then wiping it down with a chlorine solution or baking it as you suggest will work - both is overkill.
Just heating it at your 450F for an hour should surely destroy all organisms and their metabolites without any prior washing or bleaching. If you must use an oxidiser, a dilute hydrogen peroxide would be safer than a chlorine based product.