this may well be the 1970 second lancer books, inc. edition/printing
lancer books 74636 (no hyphen between the price code number and the sequence number) is also dated only 1968 in its indica and from the more staid cover art quite is likely to be the earlier.
stated as a puff- or strap-line on its cover: "soon to be a major françois truffaut motion picture" which may help establish priority (yr hmbl srppnt.'s not a great follower of films, so someothercatter'd be needed, to place when this would've likely been a live possible project).