Complex sentence: While it would be far less used than under the Islamic Republic (but still bad enough to result in several dozen deaths), the use of torture was widely condemed by Iranians and contributed to damaging the Shah's reputation.
Split into simpler sentences: While it would be far less severe or common than under the Islamic Republic, it was still bad enough to result in several dozen deaths. The use of torture was widely condemed by Iranians and contributed to damaging the Shah's reputation.