I know there are too many opinions to go around already, but some things to consider:
Think of it as an investment, not just a project(because of it's rarity).
Re-chrome anything(if the surface is broken, polish is a band-aid) that can be, instead of paying for a repro anything.
The value will go down substantially(be sure the owner knows this) if you decide to repaint it. Try having an automotive paint shop mix a matching bit of paint to do little touch-ups. A polishing wax will work wonders to bring out the original luster. Ask anyone- patina beats new high gloss every time.
If you do repaint it, trace every dart and stripe, to keep it as true to original scheme as possible.
NOS rubber is easy to get- grips, pedal blocks, etc. Again, do it right.
Anything you decide to just replace,
make sure you save the old stuff- it will add to the value down the road, even if it's in a box, not on the bike.
Get a set of NOS Torrington double-butted spokes. Save and use the old long nipples.
Re-Cad plate the fender braces.
Be proud that you had a hand in bringing back a part of balloon tire biking history that most people have only seen in pictures.