Given the 2 pound weight difference that Klein mentions in the catalog, I'd assume so. The Suntour XC components were about a pound lighter than XTR (which wasn't available yet) and XTR was about a pound lighter than the m735 XT. However, Klein also mentions a couple of options in the catalog including "machining, chainring 24, 26, 28 and 30t, and hardware" which suggests that this option would be focused on making the bike lighter, though they don't go into specifics on which hardware was actually machined. I don't think though that the machining option was part of the Super Light spec. Why?
The Klein catalog scan on RB has some notes about pricing next to each Attitude version:
XT = 10,896
Team Issue = 10,669
Super Light = 9,761
All prices appear to be in Deutsch Marks. Since the machining is listed as an option, and presumably involves extra labor, it doesn't make sense that the Super Light would include it AND be priced cheaper than the XT and Team Issue. Since Suntour was generally priced less than the equivalent Shimano groupo, and XC was the lightest groupo fitted in later years to the Adroit, my guess is that the 1990 Super Light Attitude was spec'ed with Suntour XC as you indicated. If anyone else knows for sure, I'd like to hear. Thanks.