I would love to live in a 70s house - for space and light they are on the money.
HAve to agree with ASecretLemonadeDrinker that the wallpaper might start to look tatty quite quickly in a busy family house, which defeats the point.
I would stick up plain lining paper and then paint with a vinyl emulsion - so you can wipe clean any doodles, ketchup splodges etc! You could still use a deep shade - petrol blue maybe?