[PotatoEngineer]

Can you live on 60%? That is, how hard is it if a large customer decides to ignore that last payment?

[chrismsnz]

Then it doesn't get delivered.

EDIT: Having the "finished" site on a test host (or even just a temporary DNS name) until the final payment seems like a shrewd move. The work is complete, but if you don't get final payment it doesn't go live.