If a photo shows that the post office is itself labelled "UNITED STATES POST OFFICE" on its exterior, then I would concede, would generally agree it could be renamed to that, unless there is more weight of sources calling it something different.  Pubdog and/or BD2412, could you separate off those into one requested move discussion, using the multi-move requested move option?

 Maybe some other concern here can be addressed simply.  Specifically, I don't see any problem with there being double redirects for existing articles.  If there's a redirect to an existing individual post office article, and the article is moved, that does indeed set up a double redirect (a redirect to a redirect to the article).  But, bots come by and fix those automatically, within a day or so.  Nothing needs to be done; this is not an issue to worry about.  If a name change is agreed to, then just moving the article suffices.  And then because of dab style rules, the name shown in the dab page could/should be updated to show the actual article name.  The county NRHP list-article need not be changed, it can still show the NRHP-official name and reach the article by a redirect (perhaps temporarily by a double redirect but a bot will make it a single redirect very soon).  Pubdog does that address your concern?

 More complicated are cases where there is no article, and the topic is listed as a redlink in this dab page plus in a NRHP county/city/state list-article plus possibly also in a local town article.  Then to implement a change requires finding and changing all of those to point directly to the new preferred name.  You can't set up a redirect to a non-existant article; it will be deleted promptly.  In these cases i would prefer for a stub NRHP article to be created immediately as that is easier and allows for verification that all the related pages link to the right article.  BD2412, will you please agree that we can do that or comment otherwise, rather than proceeding some other way, in cases where a change of name for a non-existent article is eventually agreed upon?