The David Olson lab at UC-Davis (who also published the isoLSD PNAS paper) has published on the isotryptamine SAR in 2020: https://pubs.acs.org/doi/10.1021/acs.jmedchem.9b01404, however they were only interested in the psycholplastogenic SAR. Rich Glennon also published on isotryptamines in the 1980s. Both have reported that iso5-MeO-DMT is active