http://www.sevenseasworldwide.com/packing.aspx
A tea chest is 61*51*41cm, which is approximately 4.5cuft. A book box as supplied by Seven Seas is 51*41*31cm (2.25 cuft). The idea is to keep each box below 30kg,
So 20 tea chests is only about 90cu.ft.
If you are really looking at 150cu.ft+ then I guess Sevenseas are not for you - they position themselves as excess baggage/mini moves, not complete house movers.