As you are removing the Narco this unit that uses the Trigg tx unit might be of interest as it will fit the same panel width, I have always found the PS engineering intercoms superb.
PS Engineering :audio select panels
What ever you decide you will be light years ahead of the Narco in terms of quality and reliability.
I bought one of these units today,
PS Engineering :audio select panels
The issue: I needed a second com radio but had no room on the stack along side my garmin 40, garmin330, garmin 496 and my PS 8000b audio panel, I planned on getting a Trigg and mounting the radio remotley from the controller in a spare 21/4 inch hole but it would have looked like **** and not been uniform, I never realized that PS made a combined unit ( audio panel with built in trigg) till I read the post above, I bought the combo unit AND antenna today for less than I could get the trigg on its own as per the advertised prices locally.
The compromise : I lost the marker beacon set up on the old pma8000b but my digital VOR has the lights and I can pipe the audio alert over to the NAV 1 on the new PAR200 so no loss there, I do however lose the recording capability but pick up Bluetooth functions for hooking up the phone which is a good trade off.
It looks like a cracking bit of kit, and at risk of brushing up against forum rules I will have a mint condition PMA 8000b leftover after the change out
Edit to add, the PAR is a direct tray changeout for the 8000b so install expense should be minimal apart from wiring the trigg as COM 2