All of the sprite sheets in the Mana Seed Character Base are 512x512. There are 13 pages, each with multiple layers for the body, hair, clothing, tools, etc. It's, admittedly, a lot of files. If you'd prefer to deal with fewer files to manage, DirePixel has just released a new tool that automatically compiles all 13 pages into one massive 2048x2048 sprite sheet. So you have just one page for each of the various layers now. Could save you a lot of work, maybe? I hear he's also got some other stuff in the works, so stay tuned for more updates!