Power-Wise: It will power them easily.
Wire-Wise: It will run them but not overclocked.
Fact is, each S3 requires 4 PCE-I ports; 2 for the main power and 2 for overclock.
You basically only need 2 ports but going that route wouldn't allow you to overclock.
The wires, the way they made them, very shittily mind you, is that one wire will power one hash card plus its overclock.
Other fact is, those wires are unable to power both sides with one wire because they are too short to cross
I have the same wires for me SeaSonics - Except I bought mine separately...
You will need a PSU with 8 PCE-I port capability... Good luck finding that under $250...
I recently updated from 550W to 650W because the 550's only have 2 ports but had enough power.
Those machines weren't made to be paired up, if you do, it's gonna cost you out the ass for PSU's...
Then if the PSU fails, you lose two machines... some things to thing about, it's not like loosing a par of S1's but I don't pair up machines.
With your 1,000 Watt PSU, you'd be able to run both machines but only one overclock.
PS: If you live in Canada, Computer Valley has a whole lot better deals than Newegg.
Hope this helped