Yeah, Reeves would have to be natural. The only steroid around then was test suspension and that was only a rumor. It's nothing that would be available to him. Nope, he just had great genes. Remember, he was only 215 lbs at around 6'1 or so. That weight is not out of reach of most people, but his perfect proportions are difficult for a natural to attain.
Reeves is one of my sources of inspiration. I really like Bill Pearl too. Mainly though, I'm in this for functional strength and speed. I got into weight lifting to improve my performance in kung fu, but weight lifting has sort of taken over my focus.