This may or may not help but I carry my Bronica SQ-A and an 80mm lens, two backs, meter and grey card with room to spare in the bottom of a
LowePro Primus AW. In the top I put lunch, first aid kit, water filter, compass, matches, some water and other things.
As with any pack it really should be picked up and tried on in a store just to make sure it fits and does what you like.
So far I've been very pleased. It has integrated tripod/tool loops on the outside, I can reach into the bottom compartment holding the camera with the pack on and it's very comfortable for a long day's hike. It has little pockets everywhere for bits and bobs. The above-linked page has specs on size etc. plus it's made from recycled plastic and has a handy all-weather cover for those surprise torrential downpours or days in the desert.
Works quite well for me. Hope that helps!
c.