How many mark viii came with lincoln phone? Can wiring be used to install newer tech?
I think you are trying to reinvent the wheel, changing the radio to something that supports bluetooth would be a better idea.
I had a 97 MarkVIII with the factory phone (so I guess you can say they sold at least one) but unlike other car phones of the era where most of it was in the trunk with a handset mounted on the dash, the Lincoln phone was stand alone. I think they were called Motacs or MicroTacs and were the earlier version of the Motorola Flip phones.
It fit into the arm rest storage, taking up most of the space and simply plugged into the car via a cradle. The point I'm getting at is, if you wanted to, you could just pop the phone out and take it with you as a fully functional cell phone. There wasn't any hardware in the car it needed to function as a portable.
Keep in mind what was in the car would be a pain in the ass to re-create. On the drivers side A pillar was the mic and button to make or answer a call. The phone also sent to the center display the lapse time of the call and the calls phone number. Remember back then, you paid per minute for air time. Since the call came in over the radio speakers, the phone also told the radio to mute or pause while it was in use. I have no idea how it connected to the outside antenna (the phone itself had one of those plastic pull out ones) but that was mounted on the back window.
So even if you found all the wiring harnesses, cradle, phone, and antenna all you would get are the looks, the phones themselves don't work anymore, the analog system (AMPS) was killed off in the 2000's somewhere. And since the phone itself called all the shots (probably built into a custom rom in the phone), I don't see how anything could be retrofit to mimic all of that.
I have to admit the phone was advanced for the time, it even had a primitive voice recognition system in it, once you added a phone number to be stored in memory, the was a call voice option which you spoke into it to learn. So if you were driving around, pressing the blue button and speaking "call Andy" would tell the phone to dial Andy's phone number for you without taking your eyes off the road.
I am surprised Crutchfield is showing numerous replacements available because I swear, up to at least 2015/2016 they had none listed. I had that car for nearly 20 years and at best all I could find was one of those bluetooth cassette adapters to at least listen to music from the phone. I dunno if they finally figured out the correct wiring adapter or what made the change, but I wish they had something back in the old days.
Have fun.