The Jabba meeting Han footage is original from the first cut of SW. They changed Jabba from an overweight Scotsman in animal pelts to the Jabba that we all know and love and added Boba Fett to the scene. Other than those two changes (and Han noticeably stepping on a tail that wouldn't have otherwise been there), the scene is original and part of the old screenplay. Whether it's reflected in the novelizations is something else altogether. Actually, I've got an original SW novelization by GL. I can check it.