Well, this is why I consult the experts! Gogar, that sounds like a great solution.
What to use for each unit?
For the modern unit, I was thinking a Pioneer DMH WT8600NEX, which is a single DIN base unit with a 10” HD screen that is mounted to “float” out in front of the dash. The screen mount allows a range of vertical, horizontal, and tilt setting. All the controls and display are on the screen, which is connected to the base unit with a short cable. The unit has wireless Car Play and all the bells and whistles. Here is a picture; I’m sure we all agree this thing would look
hideous in a classic car, in addition to blocking vents and controls and screaming “steal me”.
But wait, Pioneer sell the CD RGB150E extension cable that is 63” long and allows remote mounting of the screen. So, we just need to mount the base unit somewhere hidden, under the passenger seat perhaps, and mount the screen in a way that allows it to be either accessible to driver, or front seat passenger, or rear seat passengers (aka whiny kids) OR tucked away and out of sight.
How to mount it like that? Well, we all lusted after the Blaupunkt Berlin with stalk mounted controls:
At least, I
hope we did; if not, look deep with yourself and resolve to be a better person. For the rest of us, how about remote mounting the DMH WT8600NEX screen on an 18” gooseneck stalk, mounted to the passenger side transmission tunnel? The gooseneck is available at
https://snakeclamp.com/ and the screen could be moved to be accessible to front seat passenger, rear seat passengers, and even to the driver. Or, bent down to tuck away behind the passenger seat. E.g. in this E28, you could mount gooseneck base to the tunnel roughly below the passenger armrest (just an example, not my car):
Seem workable? I don’t know if the Pioneer is the best unit for this, it’s just the one I found. It’s pretty darned expensive, but oh well. I know some people use iPads in a similar way, but I don't think Carplay works on iPads?
For the vintage unit, it could be whatever Becker or Blaupunkt or Continental is in the car now, or maybe one could find a working Blaupunkt Berlin . . .