I'm no expert on field judging moose either. Read online the distance between the eyes on a bull moose is 10". If accurate, the spread/eye ratio in that photo indicates low-mid 30's.
Saw my best bull on 10/5 in 2013. That's today....good luck!
Yeah, when their ears are alert, depending on their age and overal skull size, they are only 20-22" tip-to-tip. I'd give this guy 4 inches on either side, and call him a 30 incher!