I have a great deal of confusion over Ayahusca Doseages, I have read 28 grams of Chacruna are sugjested for one dose, but according to my (rough) calculations this should be enought for over 50 doses atleast. How mush should I actually use of powdered leaves?

Go online and google "ayahuasca recipe". It will show what dosages to use.
Be careful with this medicine. I worked with it for 6 months before I figured out the right stuff to use.
When I first tried it I managed to take way too much and had a very scary experience. Another time I took way too much and got so sick I thought I was going to die, literally.
If you've never used it before I recommend starting out with small doses and working your way up to larger doses.
This is a magical medicine and can help you out immensley in your shamanistic journeys.
Peace