Well, actually you already know the Recommended box size for both sealed and vented enclosure.
1Liter = 0.0353 cu.ft
So if you do the math, a 43 liter sealed box is 1.52 cu.ft - that can translate into 1ftX1ftX1.52ft or a similar combination.
And for vented, 113L is almost 4cu ft. So approximately 2ftX2ftX1ft or a similar combination.
In case you opt for the vented option, the length of the port is also given in the diagram.
Should be quite easy really.