I've shot two now.
First with a 64lb bob lee, barrel tapered ash arrow and 125 grain zwickey head, almost a complete pass through.
Second was with a 60lb longbow. POC arrow and same head. buried into the paint but not to the fletch.
Either way both died a quick very very short no tracking needed death.
Personally 55lbs on a Alaska yukon is what I'd prefer no less then, though I know 50 and heck even 40 will work in the right hands.
I've shot 60lbs for quite awhile now and dont plan on changing anytime soon....works well for everything. Shoot what you're confident in. If the arrow is flying straight, and where it should be, it'll do the job just fine. As said earlier, moose are not hard to kill animals!