I only ever partly dug The USA album. Much preferred the Delia Derbyshire ensemble White Noise from a coupla years later.
Some parts of 'An ELectric Storm' are pretty psyched out (esp Black Mass track).
White Noise - https://www.youtube.com/watch?v=xZG8CE2KnBQ
The Electric Flag's - Trip OST is pretty fukt up in parts too.
Inna 60's trad psych stylee - The Lemon Pipers - Green Tambourines is pretty tuneful. https://www.youtube.com/watch?v=6LztdNWabY8
Not sure it fits the Stevo remit of Trepanned mind fuckery though.