My cube's Jund draft generally go one of two ways - efficient midrange value creatures (mostly green/black) and cheap removal (black/red), sometimes with an aristocrats (black/red) component and mana dorks to push out threats faster; or cheating out huge threats with things like reanimate / Sneak Attack / Natural Order. In theory Prossh should be able to play the role of a finisher for midrange, a sac outlet and token source for aristocrats, and a large threat for cheaty decks.
I'm away from my computer with MSE, but I like the idea of
and inherent menace. I might also want to boost the tokens to 1/1 (and retheme to goblins). That doesn't add any power to the next turn attack, but makes the two turn plan scarier, and leaves a real force behind after spot removal. I feel like that probably justifies the card at 5 mana with no menace, might try it that way.
Akoum Rockrouser is probably safe. Spending 3 mana at sorcery speed to make a 3/1 haste is okay for keeping on pressure, but it's not going to win the game by itself. I'd expect it to be one of your stronger red 2 drops, but below Kari Zev and below the more narrow ones if their synergy is present.