Just fine as long as you dont turn it on or try to drive it anywhere.
I would reccomend a beefy set of 60s or some Rockwell 2.5 tons. I have seen wayyy too many loose unimog portal boxes liberated from their component axle housing....rolling down the obstacle....into the crowd....time and time again.
I agree with Spencurai's statement (ow, my head hurts now), with one possible exception--you could use beefier Mog axles. The 404's won't likely hold up to what you want them to, so you could step up to a 406/416 and have better luck.
Personally, I'll stay away from portals--but that's just me.