Nice list ICE - here's mine

Heavyweight = Earnie Shavers
Cruiserweight = Rocky Marciano
Lightheavyweight = Bob Foster or Archie Moore
SuperMiddleweight = Can't think of any massive punchers so probably RJJ
Middleweight = Julian Jackson or Stanley Ketchel
Lightmiddleweight = Terry Norris
Welterweight = Thomas Hearns
Jr Welterweight = Aaron Pryor
Lightweight = Roberto Duran
Super Featherweight= Alexis Arguello
Featherweight = Wilfredo Gomez
Bantamweight = Alfonso Zamora or Ruben Olivares
Flyweight = Jimmy Wilde