A good source that reviews many of the currently popular and commonly utilized outcomes measures is found in Sederer,L.I., & Dickey, B.(Eds.)(1996) Outcomes Assessment In Clinical Practice, published by Williams and Wilkins, 351 West Camden Street, Baltimore, Maryland 21201. The SCI-90-R is reviewed in chapter 15, pp 89-91. The review is succinct and comprehensive. According to this review, the SCI-90 is not in the public domain, and is "...exclusively published and distributed by NCS Assessments in MN,... 800-627-7271."
I have not had experience using this client self-report inventory (used to capture the client subjective expression of psychological distress). I did investigate it as a potential part of the clinical assessment in one of my outcomes studies. I had a conversation with an NCS customer service representative, and found that the cost of the software scoring was beyond my current fiscal scope. If the financial issue is not a consideration, it is noted to be a well researched scale, and well established as a measure of current distress for patients who can manage the 90 items, and who are at least 13 years of age. see Sederer and Dickey for more information regarding target population.
A final comment: I highly recommend the Sederer & Dickey book. It provides a review of commonly used outcomes measures, their psychometric properties, target populations, permission to use information AND PHONE NUMBERS, automation information, and excellent summaries, as well as reproducing each scale at the end of the book, all in just 301 pages. I find it one of the most valuable resources for people doing outcomes work.
Hope some of this is helpful.