Hey,
we are a team of experienced programer very well versed in python. we have been through a lot of GUI based application before using python libraries(kivy, tkinter, wxpython, pyqt, outside etc). we have developed a lot of GUI for raspberry pi too.
we are sure of doing this efficiently and within time frame.
I can show you the demo of our previous work if you are interested.
we can further discuss this via messages.
thanks.