I have an RX 550 4 GB, and it plays fortnite with a mix of high~medium setting at 1600x900 and i get 60~70 fps. I would recommend that GPU.
As for psu, https://www.newegg.com/Product/Product.aspx?Item=9SIA8N26P45027 that psu looks decent, its cheap and its 80+.
to me, this case looks sexy https://pcpartpicker.com/product/hygPxr/deepcool-dukase-v2-atx-mid-tower-case-dukase-v2