Bracket for drive shaft carrier bearing

[Jason Banks]

I would not worry too much about that surface rust.

Your plan of attacking it with a grinder to get back to the flat surface where you can bolt a new carrier bearing sounds perfect.

If you don't mind the expense get the billet carrier bearing like this:
https://www.summitracing.com/parts/wst-bcb-6372
or this - https://www.amazon.com/Driveshaft-re.../dp/B0B7WTDM7R

The reason whey they welded the previous one is because the quality of the carrier bearings like you have has gone to crap, the factory style. I have one of the factory style on a truck that I have welded back together at lest 3 times. Never considered just welding it to the truck, but I guess that fixed it until the next guy has to change the carrier bearing again.