Can I operate on a response object in NGinx?

Question

I am attempting to record http traffic in a test environment for later playback with Gor.

So far I have the following configuration that makes use of the post action to forward on the request to the port I have Gor listening on to effectively wiretap the response

server {
  listen       85;
  server_name  localhost;

  location / {
    proxy_pass  http://mymachine.mydomain.com;
    post_action @post_action;
  }
  location @post_action {
    proxy_pass      http://localhost:87; 
  }
}

Is there anyway I can handle the response from the first and shuttle in on to somewhere else?

Is NGinx the wrong tool for this function?

End goal would be Request -> Port 1 and Response -> Port 2 so Gor can log everything it sees in files