My assumption was to make that case mobile, and not only around my home. If I won't find bigger case, I'll stay with this one and do a lot more modding to make it look nice.
But hey, if I wasn't living with my parents, I would probably make some external volenti cooler in basement or sth like that
You could always do something crazy, like mount the new big radiator on your wall, and mount the smaller radiator to your case. Wire them in parallel with quick disconnects on the big radiator.
Massive cooling capacity, and portability when you want it