You're concerned about /content/123/#!/content/456/, right? Well, if the client isn't modern, 301 them to #!/content/456/ and proceed as you would. Either way

You're concerned about /content/123/#!/content/456/, right? Well, if the client isn't modern, 301 them to #!/content/456/ and proceed as you would. Either way though, all this is terrible for a blog, or even Twitter.