LocDown,
I suspect that the baud rate of the GPS-HS is not compatible with the Uniden radio. The GR50 had a baud rate of 4,800 but the GPS-HS has a baud rate of 38,400 (not adjustable). You will probably need to run the GR50 again if you want positioning information sent to the Uniden Solara.
No, the Matrix 12 does not have the software to support the GPS-HS GPS Receiver.