Well, I haven't made my own changa (yet), but here are my two cents:
A gram of changa, just going from the recipes online, typically contains around roughly 200 mg of harmala alkaloids, at least if adding as straight extracted harmalas. On the other hand, if using enhanced caapi leaf, the alkaloids from 10ish grams of caapi (assuming 10x caapi leaf was used). More along the lines of 30g-60g appear to be used in ayahuasca/pharmahuasca brews.
Thus, I'm pretty sure that though a gram of 1:1 10x changa has more than enough dmt for so called "DMTea", but is totally lacking in harmalas.
If you were to take an appropriate amount of maoi previously, and then an amount of changa corresponding to your oral dose, you'd be golden, but it's not as easy as "DMTea"