Son claims his LI dad was ‘Great Gatsby’ inspiration – and someone stole his $750G book

A Texas oil honcho who says a character from “The Great Gatsby” is based on his wealthy Long Island-bred dad is suing a rare-books dealer — demanding he return a pricey signed copy of F. Scott Fitzgerald’s classic novel. William Hitchcock says his flashy, polo-playing father, Tommy Hitchcock, inspired the…