Dash fits likely means its the right width.  Its not going to be a bolt in swap.  The amount of bracketry required is probably considerable.  I highly, highly doubt that the heater box is going to fit without MAJOR rework of everything related to the heater.  The biggest thing you need to understand is that a modern dash isn't just a bunch of parts you can make fit and all will be well.  Vehicle's now are completely integrated from an electronics standpoint.  This isn't the '80s when a cluster was just a cluster and they weren't any different between EFI and carb vehicles.  Today the cluster is an integral part of the engine management.  The HVAC system is also integrated into that system.  There used to be one computer in a vehicle, an ECU (Engine Control Unit) or PCM (Powertrain Control Module).  Today every vehicle has about a dozen computers in it, and they all talk to each other to run the vehicle.  Trying to isolate one part of that is going to be difficult without an extremely good understanding of electronics.  You may see some swaps done that use those parts, but they are done by big shops that have a lot of experience in such swaps.  Typically what they are doing is swapping over everything (engine/trans/dash, etc. sometimes even down to the ABS and traction control).  That is an arduous undertaking and is done either as a showpiece to generate business or for a customer who writes blank checks.  The average guy on a project like that is going to lose steam and/or run out of money before its done.

IMO, leave the classic classic and enjoy the modern car for what it is.  If you are dead set on trying this stuff I would do A LOT of research and see if there's even any resources for doing such a swap (online articles, premade harness, etc.).  If not I'd just forget about it, or file it under "one day". 
 

I will say this about your stereo;   when I got the new Jeep Grand Cherokee there was no CD player.   My daughter put a ton.of my cds onto a digital thingy that I just.plug in.  It's a game changer!   Totally 21st century.   I just can't get her to make me one with country cds...

Bluetooth is the easiest way to listen to music, no CD player needed. The only reason to use a double din would be for a screen. Doing that dash and heater box sounds like a LOT of work.

I too slightly modified a stock '67 bezel to hold a single DIN chassis head unit.  Built in CD player (yes,  still listen to those) but also has a jack that could be plugged into a storage device or a Bluetooth receiver if I ever go that way.  I will say that having Alexa at home I love being able to hear whatever I want whenever I want just by asking it to play it.  I can probably do the same thing with my phone via Bluetooth if I want, just not that motivated. 

I have the 69 mirrors on my 67 coupe. PO had them on when i bought the car. I will tell you that if you want to use the wing window, these mirrors will interfere. I did convert them to electric using this fellars guide. 
https://7173mustangs.com/threads/power-mirror-tutorial-by-austin-vert-parts-1-to-4.40108/
There are two parts to his instructions, very detailed.
I didn't follow it to the letter, but used a switch from a 96 Exploder and they work nicely. 

 

Nos681 wrote:

BobE wrote:

Today, does anyone even listen to CDs anymore? 

I’m old school Bob.
I have cassette and CD changer. 😁
 

LOL, if it works, stay with it! 
 

John Ha wrote:

True74yamaha wrote:

I saw in Google a post that said digital dashes aren't showing their full potential so maybe will be seeing cool modern advancements in digital dashes.

I wonder how/if AI will impact/infect these.  Don't some/most of those incorporate Bluetooth?  If there's a way in (and especially if there's a wireless way in), it can be compromised.

My Dakota Digital gauge set does not include bluetooth nor any other wireless interface.  It is just a set of instruments so nothing really could be done except to make the instruments read incorrectly.