What we need are photographs of the top providers in Las Vegas in 1975.  How they looked then, and then a comparison picture of how they look today.

Also, if want more photographic evidence of what Las Vegas looked like around this same time, rent the James Bond movie "Diamonds are Forever."  It was released in 1971, so it have been filmed in 1970.  Much of the movie was shot on location in Las Vegas.  One of my favorite scenes is when our hero 007 exits the terminal at McCarran Airport and picks up his rental car directly in front of the terminal (no shuttle buses to a rental care lot needed at that time!).  He then drives to the Tropicana Hotel, which is nothing but a two story motel!  Those 2 story motel buildings still exist and are still used as guest rooms, located in back of (east side) the towers.