Here is the info for adding the NAV/GPS switch from the default MSFS C172 into the 727-100:

[Window03]
Background_color=0,0,0
size_mm=447,106
position=2
visible=0
ident=10005
gauge00=Captain_Sim.p721.P12!P12_001_ap, 20,0, 427,106
gauge01=Cessna!Nav_GPS_Annunciator, 0,0,20,20
gauge02=Cessna!Nav GPS Switch, 0,20,20,20

And for the 727-200, 727-100F and 727-200F:

[Window03]
Background_color=0,0,0
size_mm=447,106
position=2
visible=0
ident=10005
gauge00=..\..\CS_B727-100\panel\Captain_Sim.p721.P12!P12_001_ap, 20,0, 427,106
gauge01=Cessna!Nav_GPS_Annunciator, 0,0,20,20
gauge02=Cessna!Nav GPS Switch, 0,20,20,20

Now you have the solution for all of them in one place. ;)

ALWAYS backup the panel.cfg before making the changes!!!

Mark