I’ve repaired crank snouts with hard chroming, but I am not so sure it would be the best solution for the rear main seal area. I’ve read that hard chroming creates embrittlement in the base metal being plated. Not a good situation considering all the power is going through that journal.
I never had anything spray welded. It sounds like that may be an alternative. I was also thinking about turning it down, and running a rope seal.
This is a 331 hemi.

I would try polishing it enough to try and remove the high spots and go from there.
None of the early Hemi had the later seals, all came with rope seals
There might be a later seal (273/360)the same size that might work Especially one of the Viton or Teflon seals

Had one fixed a year or two ago they welded it up and ground it looked just like one of the aftermarket cranks. Cost about $180 at a crank shop sealed great no issues. The hash marks are gone but the aftermarket cranks don't have them anyway.

I had a crank shop spray weld a crank.. that end journal is stronger
than a rod journal(diameter of it)
That weld job was on a 4 cyl diesel that ate a crank

Hard-chroming is also an option.

Does anyone know the size of a rear main seal journal for a small block? Maybe that is an option. I assumed that the seal hot heads sells is out of some standard common engine (Its only $14.00)
Just by looks, I would say .020” would most likely clean it up.
Has anyone ever made an undersized seal ?

https://www.fmmotorparts.com/fmstorefront/federalmogul/en/USD/Gaskets-%26-Sealing-Systems/Gaskets-%26-Sealing/c/Gaskets%20Sealing%20Systems

Might try tech support here. If you get someone knowledgeable on the phone, he may get you to what you need.

FYI.. that welding process is called spray transfer.. I was taught that
back when I was in welding school .. its how you set up the machine
but you run it hot

hi

i have run several with seal surface .010 us and std seal .!

. This isn't quite the same mr P, they introduce powdered metal into a plasma stream that transfers to the grounded part if I'm not mistaken. I'd bet it would work fine.