It depends on how much silver is in that 40 grams of gelatin, not on how much gelatin is present.
For example, if you have an emulsion with 10 grams of silver halide / 40 grams of gelatin and another with 20 grams of silver halide in 40 grams of gelatin, if the grain size was the same in both cases, they would take different amounts of hypo. If grain sizes differed in either case, then the amount of hypo would change again.
So, hypo goes up as silver goes up and hypo goes up as grain size goes down.
Since it varies from emulsion to emulsion, this becomes an exercise in experimentation, finding out how much hypo to add, how hot to heat the emulsion, and how long to hold it. For heat and time, I suggest 60 degrees C for 30 - 60 minutes with hypo present, for amount of hypo, I have no exact value.
For starters, you might try 25 - 50 milligrams of sodium thiosulfate pentahydrate for every mole of silver present, and work up or down from there as needed. It should be added as a 0.1% solution in water and should be made fresh.