you should request the Appendix of Strassman et al. original 1994 paper directly from the authors. This unpublished appendix contains the items of the questionnaire. I am quoting literally that paper, precisely on its "HRS" section: .
Since one the authors, Dr. Clifford Qualls is in Researchgate, I recommend you to talk to him directly:
See Strassman et al. ( 1994)Dose-Response Study of N,N-Dimethyltryptamine in Humans: II. Subjective Effects and Preliminary Results of a New Rating Scale. (Arch Gen Psychiatry. 1994;51:98-108)