3 story house plus 10' chimney just for a rust job. Don't think I can get a lift to it and at $700 per day wouldn't be worth it. I would feel better about it if I had repelling gear. Roof is steep and will be a mother!
If it will cost you more to do the job than its worth and also don't feel safe about doing it, I would pass. That's me though, There is always another job that needs to be done.