The LE was a ploy to get rid of the last 600 or so HJ coupe body shells that were actually put together in late 1975. By the time they got around to finishing the design HX was the current series so they had to be remade into HX's, which meant new firewalls. The body shells were old bits as you say butthe rest was all LE special. The SL/E was built around 5/79, HZ Deville and Caprice were bult up into 1980.
The wheels are not actually HZ SL/E wheels, they were the standard rally rim of the time as used on GTS and Sandman.