Going up in size of drum will require an adjustable proportioning valve just like putting in discs, whats wrong with the factory drums? I know the factory brakes are not the greatest but going with a slightly larger drum won't be a big performance increase. I would bite the bullet and get a disc conversion if you want some serious power in your braking system.
I haven't had any experience with the product listed in your link so I can't comment on the fit etc.
