chyron8472 did a cool cover and disc art for it in here - http://originaltrilogy.com/topic/Blu-Ray-and-other-HD-box-size-STAR-WARS-covers/id/11843/page/27
There may be more artwork for Harmy’s ROTJ Grindhouse in that thread too - or the http://originaltrilogy.com/topic/Harmys-RETURN-OF-THE-JEDI-Grindhouse-35mm-LPP/id/48258 too?
It’s likely worth checking out some of other quality work on here to see what you like, what can easily be cannibalised, or just for ideas and inspiration etc.
Good luck with it - and please post up in here any good stuff you find 😃
Edit - Rikter’s Disc Collection and a few other inserts and discart etc - which could possibly be cannibalised / adapted for ROTJ Grindhouse can be found in here:-