Disc break conversion kits?

Originally we were thinking about trying to keep the stock rims and tires on the car. But, upon further review, it does not seem to be something we will be able to do. The original rims are just too small for any kit out there from what I have found. But it looks like we will size up to at least 15" for now. Don't think we want to go much bigger than that as it may look a little like one of those DUB cars. Not..... Our..... Style......