The circuit it is self is pretty simple, take in the data on one pin, parse it, format it and then display it to a 4x20 LCD module . That is the basic idea, but I might add in somthing like a mechanical encoder that would allow for changing options or changing settings in the display unit. This might be as simple as a SPDT switch if the options are as simple as two settings.
http://www.ke4nyv.com/gpslcd.htm