Raceral,
Found a site in AU specifically concerning authenticity. I don't know how accurate the info is. Appears to be a CC member.
http://users.pipeline.com.au/bryanw/...g_an_authe.htm
"Bumpers + o/riders or Quick jacks
427SC Only the SC had quick lift jack points - note the direction of mounting. The S/C had no bumpers.
Finish: same explanation as for the heat extractors.
427R Overriders and bumpers were fitted front and rear - same as AC289
AC289 Same as for the 427R."
"Grille - air splitter
427S/C The S/C never had a grille or air splitter
427R There was no mesh covering the "mouth" but it did have an air splitter - same as AC289.
AC289 Same as for the Roadster."
Hope this helps,
Jim