Yep, LX355, early design proposals for the HQ sedan had the split grille theme. The October 2019 edition of "Retroautos" showcases the HQ design development, so a mostly timely mention of the split grille idea.(see photo) Also, my "Design to Driveway" books volume 3 and 4 cover the discussions, and contain never before published photos of design proposals for the HV (never released) and HJ Holdens, which were aimed at eliminating the HQ's drooping rear end which you mention.(see photo)