Rue seeds are reported to have 2 - 10 % harmalas (though Harmaline is supposedly a stronger mao inhibitor than harmine)
While caapi vine is said to have 0.3 - 0.8 % harmalas.
50g was said to me to be a minimum dose of caapi, but I found it quite strong, in a different way than 5g rue is.
Follow your intuition.
The consciousness of plants is a constant source of information for medicine, alimentation, and art, and an example of the intelligence and creative imagination of nature. Much of my education I owe to the intelligence of these great teachers. Thus I consider myself to be the “representative” of plants, and for this reason I assert that if they cut down the trees and burn what’s left of the rainforests, it is the same as burning a whole library of books without ever having read them.
~ Pablo Amaringo