Bar / stem
If it's any help, I had my '98 LTS 1000 DS fitted with a black Profile Stiffy stem and a set of red X-Lite risers (the ones with the brace) when I bought her new. The stem was about 75mm - but at 45 degrees! Still, much better handling than the 120mm stock Kore unit and the 23 inch flat bar, which turned like a supertanker when I test rode a demo pre-purchase.
Mine was set up for DH rather than XC when I bought it, as were the other couple of guys I knew who rode the LTS when new, although I know that GT marketed it as the best of both worlds at the time. If you want a catalogue finish for the bike then go for flat bar and a Kore, BUT I never saw anyone riding a flat bar and a lengthy stem back in the day. If you want a nice handling bike that still cuts it against a decent all-mountain rig today i'd go for risers and a short stem.
I run her now with a 75mm Thompson and an Answer Carbon 1.5 riser, a set up that makes her really sweet for XC.
Enjoy - and watch those bushings in the stream crossings!