It's all in the "hack and hack unholy scriptures" up there.
But quick answer: I bought a specific chassis (around 100€) because yes, it had to fit properly. But I remember someone suggesting to simply drill the missing holes in a standard chassis.
It's not librebooted since I've had troubles with it on this board, but it's corebooted without blobs.
Anyway, you'll find all the details in the links above.
