50"ish is much more probable for sure, and that would be an incredible bull. I get that you're young, so I'll try to be a bit patient--not my strong suit. Generally when somebody tells you to try something again it's because you're first attempt was wrong. Shiras moose tend to be 8-9" eye to eye. Alaska-Yukon moose are generally 10" eye to eye. Gives you a base line to then extrapolate.I think the one in the back of the picture is bigger, and he's probably 36"-40" wide. I think the bull i saw was probably 50"ish
You're right that the bull in the back is "bigger" because he definitely has more paddles and better brows. But those bulls were within ½" of each other on width. And the "smaller" bull was 50" on the nose, with the bigger bull coming in slightly narrower. The smaller bull has a tine that tips out and gained him a few extra inches. Both are "above average" for Utah bulls these days (and were 15 years ago when I took those pics, but less so).
Here's a Colorado Shiras bull a hunter posted on another website from this year. How wide do you think he is, knowing that those two were ~50" wide?