Barry Goldwater was NOT endorsed by: Nelson Rockefeller, Governor of New York; Jacob Javits, Senator from NY; Kenneth Keating, Senator from New York; William Scranton, Governor of Pennsylvania; George Romney (Governor of Michigan), and a whole slew of others who went nowhere in Republican politics after this.
But, here is the vital difference. LBJ succeeded in painting the false narrative in Conservative areas that he was a moderate Conservative; this time millions of blue collar Democrats understand what is at stake. (Goldwater did get decent blue collar grassroots support, but not on the scale that Trump will.)
Further, LBJ, mistakenly was seen as more trustworthy by a broad spectrum than is Hillary. If we focus on the issues, and get out our vote, we should win.