
Update: The release of the soundtrack to Kamasutra Vollendung der Liebe (Crippled Dick 2009) credited to Irmin Schmidt & The Inner Space clarifies everything. This track appears on there as 'In Kalkutta III', recorded in 1968 for the soundtrack the film by Kobi Jaeger.
Not a bad guess then, this was recorded when David Johnson and Malcolm Mooney were in the group, prior to renaming themselves as Can.