You need a HDS display for the Broadband Radar. GlobalMap can only use the LRA1800HD and LRA2400HD models (and the old obsolete analog radars)
Here is what I would have done: Buy a HDS with sounder, connect to one of the GlobalMaps using Ethernet. Use the new HDS screen as plotter/radar screen and run the HDS broadband sounder at the GlobalMap. Sell the other GlobalMap and the broadband sounder.
To get gps data from LGC-3000 to HDS for redundancy you also need to connect the HDS to the NMEA 2000 netork.