Changing the URL from the original VIP address to the Node's address

If you're referring to the URL displayed in the browser's address bar, then understand that this is actually more of a DNS issue than anything else. The contents of that bar are a function of the browser itself and are generally not influenced by the HTTP traffic. For example, in order to change the address bar, you must issue a physical redirect. That redirect will cause the browser to have to look up this new URL and then go there. So in your case, the internal name would have to be both resolvable and accessible. Assuming this is not what you want, here is an alternative:

In the HTTP response event, take the chosen internal server (name or IP) and insert it into the HTML payload. You could, for example, add it to the bottom of the page, or as a hidden value inside the HTML source.