Silencer removal

[smoothoperator]

A couple of questions on the silencer and headers. The silencer is in reasonable condition but I'm struggling to remove it from the headers, any tips welcome. I plan to get the headers rechromed, there is a dint on the underneath of one of them, otherwise they seem OK. Can a braze repair be used to fill the dint or is it best left alone? Also, how much prep should I do on the headers regarding the corrosion near the top of them?

Images

https://photos.app.goo.gl/1NzzKNfENJQkwMsc6

[boilermaker1]

One of my header pipes was dented like yours. I had it filled out with mig weld and ground down.
Unable to see repair after rechroming