I was just looking through Snu's Garden of Eden and found the following information on pp. 60 -

Harmine inhibits MAO efficiently from about 1.5mg/kg; harmaline does so from about 1.2-1.3mg/kg (expect personal variations).

My weight is 85kg, so would require -

85 x 1.5 = 127.5mg of harmine.

this is much higher than the 39.27mg of harmine prescribed to me according to dosage information provided in the attached paper.

from personal experience I would be going with the 1.5mg/kg to produce the Ayahuasca effect.