With reference to this
service manual, which form factor do you have? Might I ask why you're looking to change the chassis of the prebuilt? It seems fine on it's won to accept any hardware upgrades(and perhaps a PSU upgrade). You will run into the issue of connecting the front panel headers of the case to the board since the pins are not labelled on the PCB(or so my research shows me).
Also, you're only going to drive the return on investment on the prebuilt towards negative, I'd suggest leaving it as is.