1) Try and go with a R9 280x or r9 285..     really worth the maybe $40-$60 more ...

2) Go with 750W or higher PSU..   Both AMD CPU and GPU are power suckers.. also if you want to Crossfire (dual cards) in the future ..  A 750W+ PSU will be needed..

Normally this is true, but the R9 280/280x/290 are very power-hungry. They can get as high as 280 Watts consumption. If his CPU wasn't also power-hungry he could likely get by with 500W, but his CPU has benchmarked to max at about 160W. That can be up to 420-440W usage for the CPU+ GPU alone. Considering that many of the average 500W rated PSU's really run around 450W, I wouldn't risk it. Heck, I have a Pentium G3258 (max watt consumption about 70 w) and an 280x, and was a bit worried that my 500W PSU wasn't enough. There are some good deals on 550W-600W PSU's though. I bought my 500W PSU for $40 and got a $20 rebate, which went to my Pokemon Alpha Sapphire purchase. The 600W version was only $15 more. 

Looks solid, although I would try to get an i5 if possible. Also, try and see if you can pick up a 280x for cheap, the performance difference is worth it. I would also go with a 700W+ PSU for headroom in case you decide to upgrade down the road.

Oh yes. This! The R9 280x is very long. Make sure you get at least an ATX Mid-tower case. Even then, I had to take out the optic drive cage in mine to have it fit snugly. 

Well I checked my sources before saying this. A whole system with overclocked 280X and a 4770k consumes about 350W. The 8350 consumes about 100W more than the i7. That's why 500W would be fine(if it is a good PSU it will deliver close to 500W) and 550W to be safe. Everything above that would be wasted unless he plans to overclock his CPU and get an overclocked 290X. I'm not used calculating with AMD.

My next system will be with an i7 and big Maxwell and I'm planning on getting a PSU around 400W and not bigger than 450W.

Most people go by the idea that you do DOUBLE your max CPU/GPU .. SO if its 350W.. You would want to do 700W+..      and I like I suggested..  going 750+ will allow him to Crossfire later on.. 

Unless you never do crossfire and sit on wasted efficiency throughout the PC's life. A 700+W PSU will use an unnecessary amount of power on idle systems.

And if OP one day decides to do CF there will be money for a PSU upgrade as well. Though I don't know anyone who would suggest CF on then outdated midlevel GPUs.

Umm. No..  A PSU does NOT use more power the higher wattage you go...  it USES what is USES..   A 1000W does NOT use more power then a 500W .. Unless the parts of the computer are consuming it..    

Also..  It is NOT just about Crossfire..  even PCWORLD recommends this:

"Most power supplies hit their peak efficiency levels with loads in the range of 40 to 80 percent. Building to about 50 to 60 percent of a PSU's capacity is advisable to achieve maximum efficiency and yet leave room for future expansion."   

So again..   a TDP (total design power) of 350W.. it is RECOMMENDED by pretty much most PC builders that you do 700W or more..

The 450W I suggested aren't TDP but the measured actual power consumption of the whole system. Which means the system will actually draw even less from the PSU due to efficiency rate.

And yes, higher power PSUs are very inefficient with idle loads which are usually below 20% or even 10%. At this point the efficiency plummits down to levels of just about 60%.

A 1000W PSU will always draw more power from the socket at idle than a 500W PSU. And both will draw about the same at 450W load.

Add to that the fact that games won't run at the highest power at all times, especially if you lock the FPS. Which means while the load is going down to 300W the 500W PSU will be at peak efficiency while the 1000W PSU will fall a good way below that. Hence drawing yet again more power from the socket than a smaller PSU.

Here are some benchmarks for the 280x. 

http://www.tomshardware.com/reviews/radeon-r9-280x-r9-270x-r7-260x,3635-18.html

In Metro: Las Light it averages at 207 Watts. That means it likely peaks at the TDP of 250 Watts. 

Here are some benchmarks for the FX8350

http://www.tomshardware.com/reviews/fx-8350-vishera-review,3328-16.html

It averages at 182.21 Watts. 

206 + 182.21 = 388.21 on average from the GPU and CPU alone. 

Now the peak power consumption can be higher than that, and it will be with more demanding games. Basically it depends on the model and the brand of the power supply. There is an Antec supply that my friend is looking at that really can do 550 watts continously but is rated for 500 watts. Meanwhile certain Corsiar supplies are rated at 500 watts and really only output 450 watts continously. Both are highly regarded brands. Nevertheless, if you can consider a situation in which the CPU and GPU can peak within 50 watts of your power supplies rating, then that isn't enough, because that means your PC will shut down at those peaks (there are other components drawing power.) And if you ever were to consider the concept of overclocking (even if you don't think you will now) then you are pretty screwed. And it is all to save $10-$15 (usually the cost difference of 50-100 more watts with the same model.)