Being an annoying literal: it would be 150kg of cooked rice from 50kg raw, and I assume that's 200kg of unprepped lamb with bone and such, so gotta work out to be 1:1 at least plus the veggies to consider.
But idk, even my local place is not quite that generous, heh
Good lord! That much ghee ... how do you even source that?
Recipes with ingredients denoted in litres and hundreds of kilos? I mean - I worked in a restaurant long ago & remember dumping 20lb sacks of flour into the dough mixer, but this is some next-level cooking!
You can get big cans of the stuff. I usually get a liter or two at a time at regular Desi/Arabic grocers, so bigger quantities being available is pretty much a given.
25 mL (about 1.6 TBSP) each per serving maximum, as that's a "don't use more than" quantity. For a special occasion meal, that's actually not bad at all.
Your average French chef would die laughing at worrying about a couple tablespoons of butter in a meal.