Very nice bike! Campagnolo 8-speed shifts as well as any modern mechanical systems, as long as the right-hand lever G-springs and spring carrier are still fresh. If the shifting is crisp and the right-hand lever holds a gear correctly, you probably have a few '000 miles left before these two items have to be replaced.
If it was me, living in the land of hills, I would replace the cassette with a 13-28, which are still available. Miche also makes these. Longer chain of course. Need still lower gears? Then replace the crankset with a triple (Campy) and the rear derailleur with an 8/early 9-speed Campy long cage. All easily sourced on Ebay or this forum.
As far as the bars, I prefer the traditional round-profile drop bars, with the Campy cable housings taped on both the front and rear. Then, when wrapped with bar tape, this results in an oval shape, which provides more surface area and comfort for tired hands. Keep the bars, unless they are too narrow or wide.