Republican Roman Medium Infantry

Having got some free time on Saturday morning I decided to finish off painting my Roman infantry.
These guys still need to be based washed with a black wash and varnished. I'm thinking of basing them on 1.5cm² plastic  modeling card and using magnetic signage material fixed to the bottom side of the plastic card to fix them to a steel base (low carbon not stainless as alot of stainless is austentite and non magnetic).

I'm not sure if to do them 5x3 with the 3 command figures at the back behind the block or 5x3 with the command figures at the side making it 6x3

The first pic is of the group as a whole 18 figures and all from the Italeri Republican Roman infantry set

Below is a close up of the 3 different infantry poses and then one of the 3 command figures