What do you consider a good arrow/broadhead combo for those overweight potentially nasty black bears?
Well there's lots to choose from pou there, and this will depend on the amount of $'s you wanna spend.
If you're hauling in the 60~70# range and want to conserve on the spending, the XT series Gold Tip 5575 with the G5/100G-BH will accomplish the job--providing you place the arrow in the boiler room.
Accuracy & shot placement will get you a kill with a 40# set up--you're pushing 60 plus. A 27" XT shaft (5575) W/100G BH will carry you over the 400 grain mark and your speed and KE will be just fine for that black bear!!
All the best and shoot straight--you get your meal!!