that is a clone of the older chenbro RM41416 (i use one of the Chenbro cases) from the looks of it chenbro (and some Dell) skids would work. there are skids with mounts for 2.5" drives available. the longer PSU bracket would accept a N+1 4u style triple PSU if you wanted to go that route, also.
One thing you might want to consider before going to a bigger case is if you want to increase the capacity on some of your drives. After all, consolidating five 1TB drives to a single 8TB drive might be of interest, not to mention 18TB drives.
Your parts, your money though, just thought I should point out a potential different direction that might be more what you want. Most people think they need more space than they do. That said, if you do need more drive bays, going for a rack is 100% the right call!