Graham worked the Miami Superbowl of Wrestling show against Race, title vs title, in early 78. Probably worked some other dates since he was a name in the territory.
Florida TV was available in the New York area as well.
Most fans in Florida wouldn't have been familiar with WWF guys outside of the ones that worked there before, like Graham or Backlund, unless you followed the mags.
Backlund staying Florida wouldn't have really benefitted Graham much because he wasn't going to be pushed ahead of Dusty or Jack Brisco as a top star.