Got my Rosewill case today. The inner dimensions are:

Height: max 17cm
Width: max 41cm

From the front to the mainboard, it has around 40cm of space.

Let me know, when you need more info.

Edit:

• Got rid of the hdd cages (+ three front fans)
• I can freely place the middle fan "wall". i guess it goes close to the mainboard (My Asrock H110 Pro BTC+ has a width of around 21 cm) with enough space left for the psu cables. Edit 2: Or maybe to the front, as done here: https://www.youtube.com/watch?v=BEsev9vTeHI
• I could use the other long and thin piece as gpu holder in the front. But i hope you come up with something less improvisational than me