Custom car build, old with new tech. MITM interface?

I’ve built a custom 1997 Lincoln Mark VIII (OBD2 j1850 PWM) with a drive line from a 2003 mustang and it’s my pride and joy. I want to update the electronics of the interior to modern standards. Like a digital dash (LCD screen), high tech infotainment center stack (think Tesla center stack), 3D top view cameras, GPS Theft recovery, Parking assist, controllable interior lighting, etc.

I’m starting to do the research / testing on what’s needed to achieve this monumental project. I started out with a couple of RPi 3 and a naked Arduino Mega 2560 and come to the conclusion that the ODB2 port is too slow for getting the information I want for the instrument cluster. I also live in a state that has emissions testing so I’ll need to keep my OBD2 port for testing. My PCM seems to handle the drive train and it’s supporting components (fuel pumps, o2 sensors, ABS, etc.) all on it’s own and the rest of the car is a bunch of independent modules or j1850 networked.

I’ve found a couple of development boards (Renesas H3 is the leader right now) that could be the core of controlling all of the new Canbus based things mentioned above, just a lot of programming. It seems to be a ton of ready made plugins / modules and all you have to do is plug in some values.

Questions:

Can I use the Macchina to be a Man in the middle as a translator to control these various j1850 modules (seat, moon roof, HVAC, interior lighting, etc)? In my idea world i’d have the Macchina wired into the various j1850 modules and translate a canbus command / request from the H3. Worse case would be to replace all of the modules with wiring from an Arduino Mega, I’m willing to do it but the programming would be massive and a nightmare.

Anyone on this forum that would be Subject matter expert / Guru on what I’m wanting to do and would be willing to talk / bounce some idea off of?

Am I going at this the wrong way? Idea on how to add a Canbus layer to my car but control / interface into the existing legacy infrastructure?

Yes hardware wise it would work as a stand alone setup. But currently the software is not developed to a point to allow that easily.

The M2 is based off the Arduino Duo so it is highly programmable.

Rodney