Practicality of Custom Dash and Door Panels

[Drooopy]

I am in a bit of a conundrum with my Bronco. I primarily use it on road with some fire roads and such mixed in. I am slowly saving for a go-fast suspension as eventually I would like to have it capable of going west. However, I need to do something with the factory interior now. The plastics a cracking up badly and the wiring insulation breaks if you bend it a bit. Trying to install a new head unit ended as a total mess.

I would like to build myself a new custom interior. I am good with fabrication and the basic building of the dash and running wiring isn't a big issue. My concerns are with the unknowns. Will I be able to find all the plug ends I need to replace the wiring harness? Will I be able to keep the factory steering column without too much issue? Will I be able easily use the factory speedo (psom) while replacing all the other factor gauges without too much trouble? Is there an aftermarket way to control the factory heat/ac or do I need to keep the factory controls? Are all of these things minor issues and I am just screwing with my own head?

Would love some input from those who have done this on what the big things to look our for really are.