Okay, good luck finding a developer who will check your project for free, spend their time to research and analyze it for a deep understanding of your needs, and then give you a fixed price.
Of course, the developer's price will not be very high because you have already done most of the work, and the developer will only need to do a very small amount of work to achieve your main goal: change a huge codebase that almost works and make it understandable. Easy.
