The power supply he wants is flat out TERRIBLE.You can see that from its reviews online.
If he wants a good modular power supply with plenty of power at a low price i suggest the Rosewill Hive 750http://www.newegg.com/Product/Product.aspx?Item=N82E16817182133
I also don't know if the Antec Three Hundred will fit the graphics card.The case has 10.5 inch clearance and the card is 10.2 inches long.
If he doesnt that to happen you should take a look at the case below.http://www.newegg.com/Product/Product.aspx?Item=N82E16811147161
Also he should definetly upgrade to a HD 7870.It's not much more expensive but its a LOT faster.http://www.newegg.com/Product/Product.aspx?Item=N82E16814127681
If you cant afford the HD 7870 then simply switch thr CPU form 3570K to 2500K.The 2500K is only 1-2% faster than the 3570K (when both OC'd) and you'll save some money.
Also the motherboard he chose has no VRM cooling so it's a very bad choice if he want's to use a 24/7 OC.
The Asrock Z77 Extreme4 is a superior choice.
And lastly you dont need any thermal paste if you're going to use the stock cooler it's simply pointless.
He probably wants thermal paste becasue he saw the article on how it fixes Ivy Bridge's temp problems.But he forgot to see one thing.The opened the chip and applied paste inside it for that to work.