Need help picking case and psu...

Rhys Renham

Honorable
Sep 10, 2013
48
0
10,530
Hello forum,
I have roughly £350 to spend although i wouldnt like to spend it all.
I am buying a r9 270 but i only have a 300w psu therefore it will not end well so i am looking for a new case so that the graphics card can fit in the case with air getting to it and im also looking for a psu, If someone could recommend me some for a reasonable price (prefer someone known for quality such as corsair or seasonic) id be grateful.
My current specs are:
300w psu
6gb RAM
Radeon HD 6770
AMD Athlon II 760k
Another thing is the motherboard i am using is fairly old so should i buy a new one or keep it as it is.
Thanks a bunch