Close call as the newer Heritage have changed their spine ratings.The 150 went from .487 to .495 spine and the 90 went from .608 to .688.The 150 may be a better choice as they will accept a heavier insert if needed.The 90 is a slightly smaller diameter arrow,only choice you have are the standard aluminum insert and is a lot weaker spine then the older 90's.I would try the 150's with the point weight you want to shoot and trim and tune from there.The older 90's may work also,I don't believe the Bear Montana's riser is not cut past center.