restore slant exhaust

I have the original exhaust (I think) to my swinger, and want to clean it up and look for holes or damage. It used to work, but I don't know if it had any problems.
I don't have the money for a new exhaust, so need to clean this one up and get it working. What's the best way to clean it? The muffler is almost rust free but the rest is all rust.