That sounds like a really nice combination. I have just recently fallen in love with aMT, and can imagine that would be an insanely euphoric trip. The Ketamine would add a level of weirdness to the trip, that would synergise well I feel. I'd stack these generally in length order - start with the aMT, once the come-up is finished, add the Mushrooms, then add the Ketamine when approaching the peak on the Mushrooms (this will probably roughly coincide with the aMT peak too). Tell us how you get on - sounds like bliss!