Question from a different angle: If you are only concerned with how a page looks to search engines #2 through #99, why does it have to be kept out of google at all, whether by 403 or noindex or "Sorry, we've already rented that apartment" or "Pay no attention to the elephant"?
:: detour to read OP three times over ::
Are we looking at two parallel sites under the same domain name, one for google and one for everyone else? And the "everyone else" pages would be actively harmful to pages in the google-permitted area? I can't see any other reason for concealment.