Having powder coated several frames with chrome socks, if the chrome's good, the powder coater will media blast it to roughen it up. If it's beat up, I sand it before taking it to the coater. If it's flaking, I sand it until only chrome that's well adhered is left. If you do that, though, you need to feather the chrome into the bare metal, or you'll have pock marks in the finish.

If you can find someone who will chemically strip it, note that the same chemistry that removes the chrome will eat into the brazing filler. It's unlikely it will weaking the frame, but lug shorelines may suffer, and the brazing might look a bit undercut.