My advice is put some SSD in, at least for the system ~250GB, I would recommend ~500GB for games. And That PSU is good, but your configuration will never drag as much as 750W, I think 650W PSU would be more suitable and also more affordable.
Case is very subjective but my suggestions of cases I like: NZXT H510 [Elite], Fractal Design Meshify C, Phanteks Eclipse P400A(S)