Nice bikes, especially your black Joe Waugh. It's rare to see splatter bar-tape look so good!
The seat post is currently a Selcoff Titanium, and the stem is a 3T ahead corsa.
I would like to replace these with Campagnolo Record parts that would match the rest of the groupset.
Campagnolo have never made stems. The one you have may not be the most elegant, but at least it's Italian, and from about the right period.
There wasn't a Record seatpost in the '98 catalogue, but by '99 you have the titanium-shaft Record post:
They're hard to find, and a good example will cost you an arm and a leg. The Selcof you currently have isn't a bad alternative.
Note that your Ergo shifters are also from '99 or later. '98 was the only year of the newer, rounder hood shape when Record used aluminium rather than carbon lever blades.
There's a good selection of Campag catalogues in the Retrobike archives:
http://www.retrobike.co.uk/gallery2/v/M ... atalogues/
Calmes dans le demi-jour
Que les branches hautes font,
Pénétrons bien notre amour
De ce silence profond.