I was going to suggest just grounding it but that wire is old. I dunno. I'm glad I bought my house when it was new and don't have to worry about what jacked up shit a previous owner did. I'm noid like that tho.
It depends on what wire is in the house.
I would at least run new wire on a dedicated breaker.
No sense in being unsafe.
If it has proper gauge wire in good shape I would ground it.
The house we just got was horrible. Spent the last two years undoing fuck ups.
The wiring and plumbing. Hell they had gutters run underground to the septic. Had to rent a backhoe to fix it.
I can't stand people cutting corners. I guess it comes from being in the military and that "attention to detail" they drive into you.