Zeke had 54 catches last year. I expect him and Pollard to factor heavily in a new and improved screen game.
Drew Brees has the record for the most completions in a season. In fact he has the top 3 2016, 2011, and 2014. He had 471, 468, and 456 in those years, respectively. For context Dak had 388 last season. In those record years the pass catchers at or over 50 were:
2016 - 92, 78, 72, 58
2011 - 99, 86, 80, 52, 50
2014 - 85, 83, 59, 53
All of this is to say that you usually have 4 guys, maybe 5, grab 50 balls. You also have to factor in that Zeke and Pollard are definitely going to carry the ball 350-400 times. In McCarthy's last 5 years his TEs caught 74, 73, 60, 69 and 49 passes. Big Mike likes his TEs (no pun intended).
I would also argue strongly that Cooper and Gallup are the best 1-2 punch Big Mike has had in a long time.
In my humble opinion we can expect Cooper, Gallup, Jarwin and Zeke to get at least 50 catches. Cooper and Gallup should be 85 plus guys easily. Cobb grabbed 55 last year so it's hard for me to see a rookie getting that level of production. I think Pollard is going to grab 30 to 40 passes as well.
Lamb is going to be a good one, no doubt. I just see him taking time to work into the offense. I expect his production to come mostly in the second half. If the under / over was 50 - I would take the under.