The Raleigh Sprite

My late 1970's Raleigh Sprite is still in pieces. The chrome handlebars and brake levers cleaned up fairly well with aluminium foil and Coca Cola, but I've bought some 'chrome polish' to finish them off. The seat post is having the same treatment.
Unfortunately there is some deep pocked rust, but the bike is about 40 years old, so for it's age it's doing quite well. It'll look dandy when it's finished!
There's a lot of rust on the frame, too.
I might use 'rust remover', but I'm leaning towards vinegar at the moment as the decals are in good condition and I don't want to lose them.
My question is - should I use a hard car wax or lacquer to seal the bare spots? I'm going to try wax as I want to keep it as original as possible.
We'll see.
The replacement rear derailleur came today. It looks really nasty, but it'll keep the bike going. When (if) I sell it - I'll include the original.
How much work/money do you put in until it becomes silly?