It looks like you may need to mount the GPU vertically. I’m not a big fan of that configuration. But plenty of people have done it. Keep in mind though that the sim works GPU’s quite hard, and unrestricted airflow is important to keep temps down.
Also, what ITX motherboard are you looking at?
You need to be very careful with component dimensions in a case that small.
Maybe take a look at the Lian Li O11 Air Mini ATX Mid Tower Case (about US$100.) Includes 3 fans. Add a Corsair RM850e (2023) 850 W 80+ Gold power supply (about US$114.00.)
Having a little bigger case gives you flexibility, and more importantly, better airflow.