You should definitely upgrade to at least the 15/16 MC... everyone said it's not neccessary, but I don't see how it is even possible.

I am not sure about other brands kits, but unless the kit specifically says that it was designed for use with your original MC, then you NEED to upgrade. Rotora's kits specifically state that they were designed to utilize the stock MC.

The prop valve, on the other hand, isn't definitely needed, but wouldn't hurt.