Yeah, I agree that it's really obvious. Maybe do some research on a surname website and find a name with a meaning that has to do with water or something? Here's a website I use a lot, I think I got it from someone else on Nameberry:
Just go to the index and pick a letter that you think would mesh with Silas Jason. There's a lot of history on each name
I agree with everyone elses opinion; the surname is a bit obvious...
A different Greek last name might work; like 'Constantinos'
The surname is way too obvious. Silas on it's own works fine. So does Jason, though if it's involved at all with Greek mythology, it might be worth it to note that there is a Jason in legend. And on top of that, there is an upcoming BBC series based around Atlantis and the main character will be names Jason.