These were apparently done in 1978 (?), so before Dino De Laurentiis was involved, and obviously based on the Oliver Stone script.
archive-editions.com/Resources/DDD_Vol2_19.jpg?108
archive-editions.com/Resources/DDD_Vol2_20.jpg?108
Pics come from this book: archive-editions.com/jimdanforthlayo1.html
I'm assuming more of his CONAN designs are included in the book...