Dan,
Is the Ensolite (original wall covering) already painted? If it isn't, you'd be surprised how much "freshening" (in the form of scrubbing) you can do without damaging it, so you might find that you don't need to
paint it.
If it's already painted, there are a lot of threads on the forum describing how to paint the Ensolite. Some of them will be described as pertaining to Bolers or early Scamps, because they used Ensolite on their walls as well.
Raya