You don't need 150 gr of powder for quicker kills. My elk load is 90 gr of powder with a 350 gr bullet. That is with 777 or BH 209, so that is equivalent to about 105-108 gr of pyrodex/black powder. Bullet selection and placement are the key. I would try some of the bullets listed above with good track records.
Any load in the 100-115 range that is accurate and uses a good bullet will get the job done.