The rear derailleur freewheel/cassette and chainwheels are probably the first to be changed on a bike.On a vintage bike in excellent condition (that apparently had a lonely existence in a garage) all of the components likely are original.When it comes to the ultimate in cycle design then the Campagnolo Delta brake will rate very high.
The most likely components to be original are the stem, handlebars, seatpost, and brakes.
The Delta was so complex that it would be next to impossible to correct this on the road.
Setting up the brakes is very tricky - an engineering degree is a good starting point!
By the 1990s, Campag were offering several group sets in different quality and price ranges, for both racing and touring.
Above is the Chorus long cage model, 1993, featuring a swivelable parallogram with A and B positions for close- or wide-ratio blocks. Note also that the parallelogram now runs parallel to the chainstay, unlike the design from the Gran Sport to the C Record.