I managed to get the pop up version of the GTN750 to work with the flysimware FA50, however after hours of trying I'm at a lost on what I need to do to get it integrated in the VC.
The right entries show up in the panel config but I fail to get it to show up.   Below is the pertinent panel entries.

 

[Window00]
file_1024=HANGAR.bmp
size_mm=1024,1876
window_pos=0.10,0.05
window_size=0.30,0.90
BACKGROUND_COLOR=0,0,0
visible=1
ident=CONTROL_PANEL

gauge00=CONTROL_PANEL!clipboard fuel repair,    50,320,340,320
gauge01=CONTROL_PANEL!clipboard map,            50,650,340,300
gauge02=CONTROL_PANEL!clipboard atc,            50,965,340,280
gauge03=rxpGTN!GTN_750_1,50,1250,340,220
gauge04=CONTROL_PANEL!clipboard CABIN LIGHTS,   516,454,37,37
gauge05=CONTROL_PANEL!clipboard DOME LIGHTS,    516,524,37,37
gauge06=CONTROL_PANEL!clipboard RECOG LIGHTS,   516,594,37,37
gauge07=CONTROL_PANEL!clipboard PANEL LIGHTS,   516,664,37,37
gauge08=CONTROL_PANEL!clipboard kneeboard,      445,1005,530,400
gauge09=CONTROL_PANEL!clipboard OPTIONS,        485,1760,520,110
gauge10=CONTROL_PANEL!clipboard COLDSTART,      550,800,300,70
gauge11=CONTROL_PANEL!clipboard HOTSTART,       550,870,300,70

 

[Vcockpit01]
Background_color=0,0,0 
size_mm=900,900
visible=1
pixel_size=900,900
texture=$gps_1

gauge00=Falcon_50!SYSTEM,             0,0,2,2
gauge01=Falcon_50!FUEL_USED,          0,0,2,2
gauge02=Falcon_50!FUEL_SYS,           0,0,2,2
gauge03=Falcon_50!CLICK,              0,0,2,2
gauge04=Falcon_50!SOUNDS,             0,0,2,2
gauge05=Falcon_50!KEYS,               0,0,2,2
gauge06=Falcon_50!AP_MODES,           0,0,2,2
gauge07=Falcon_50!SPD_HOLD,           0,0,2,2
gauge08=Falcon_50!ALT_HOLD,           0,0,2,2
gauge09=Falcon_50!ENGINES,            0,0,2,2
gauge10=Falcon_50!START_SYS,          0,0,2,2
gauge11=Falcon_50!PRESSURIZATION,     0,0,2,2
gauge12=Falcon_50!TEMPERATURE,        0,0,2,2
gauge14=FBGS_XMLSound_x64!FBGS_XMLSound, 0,0,1,1,Sound\FSW#121
gauge15=Flysimware_Fuel_Dump_x64!Fuel_Dump,    0,0,2,2
gauge16=rxpGTN!GTN_750_1, 0, 0, 2, 2,NO_BEZEL
gauge17=rxpGTN!GTN_750_1,10,10,900,1036,NO_BEZEL
gauge18=rxpGTN!GTN_750_1,66,190,596,509,NO_BEZEL
gauge19=dsd_p3d_xml_config_x64!config,  5,5,5,5, ./gauges/dsd_F50_xml_config_x64.ini
gauge20=dsd_p3d_xml_sound_x64!Sound,  5,5,5,5,
gauge21=Falcon_50!ANNUNCIATOR,     0,0,2,2
 

Solved.  Found the issue was with the Flysimware gps management tool located at C:\FLYSIMWARE.   Ran the GPS panel layout app and selected Reality XP GTN 750 I'm up.  I'm going to recheck documentation to see if that's noted in the flysimware manual.