sorry, I have to disagree.
The OP specifically stated a problem that even a well tuned carb isn't going to overcome.
Large changes in Alt always caused problems and won't be fixed that way.

Beyond that, I think you are mistaken about being obsolete or not having parts.
I stated that case out very clearly in my post about being careful about that, but it isn't as big a deal as you make it out to be.
The only thing I changed out when I went to a different system was the ecu.
The stock 5.9 mag parts remained the same between the two. the o2 sensor stayed the same as well.
All of that is off the shelf from any parts store gear.

If they ecu craps out, it is a specialty part, however, finding another one to work with my existing gear isn't that hard and wasn't that hard 5 years ago, and it is even easier now.

I am a luddite in that I don't like new tech gear for the sake of tech gear, but hear, I find it is worth it if you can afford it.