I apologize for the delay. I didn't get a notice that you had responded.
What are the plan dimensions of the shipping containers?
The posts can 4x6 doug-fir no. 2 and the beam can be a 5.25" x 14" 2.0E LVL.
In that case you can use 5.25" x 11.25" 2.0E LVL instead of the 14"
Steel can be W8x15