My 95 Zaskar LE that is stock weighs 24.6 lbs. It's a large/20" frame. The only changes between original and now are reissue Smoke/Dart tires instead of the original Tioga Psycho's and the addition of Onza stubby bar ends. I also switched out the Judy SL elastomers for coil springs. I wouldn't call it heavy. The equivalent Xizang would weigh 23.8 by your calculation rather than 24.6.The 90s Zaskar frames are actually very heavy. I had a 18" 96 Zaskar and it was over 1800g if I remember correctly. At the same time, a same-size, same-year Xizang was 1400g.
The lightest listing I've seen has been 1997 Trek OCLV 9900 Pro Issue frame from 1997 with 1264g.
Regarding Shimano parts, the XT M737 was lighter (esp. crankset) or at least as light as XTR M900/910.