You'll really want a GTX 970.
Anyways this is something I just quickly put together for you:
http://uk.pcpartpicker.com/p/JKzZCJ
I changed the CPU to an i5-4690K.
This CPU should be good enough and it'll save you money to spend elsewhere.
If you want to go down the AMD route to save more money you could look into AMD FX8320/FX8350.
I removed the cooler, stick to the stock cooler.
The mobo was horrible imo so I changed it to a decent Z97 mobo.
You could have a look around to try find a better one or one that offers better value.
I changed the RAM to a slightly faster Corsair ram that is also cheaper.
I changed the HDD to a WD black because Seagate has a very bad reputation for consumer HDDs and I wouldn't trust em.
I changed the GPU to a GTX 960, as I said earlier, you ideally want a GTX 970 which costs a £100 more. This won't give you your ultra but it's better than the two you had in your build. You could go down the AMD route with a R9 290 (or 290X) which is sort of the GTX 970 equivalent but keep in mind those AMD cards are power hungry.
I also think the SPEC-03 case would be a better choice.
I added a AF120 fan to add to the front.
For PSU, paying a few pounds more for the Semi-modular edition might make cable management a lot easier.
ODD is just the cheapest dvd writer, iHAS ain't too bad imo.
I left out the OS, I think you could pickup W7 Home premium at a decent price or use your existing one if you have one.
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Anyways you can do some more research and play around with the parts.
I think you might get more responses if you posted in Systems Forum -->
http://www.tomshardware.co.uk/forum/forum-31.html
If it's possible to increase your budget, it would help you greatly in getting a better GPU.