Removing bottom bracket from 79 peugeot frame
Usually one only needs to remove the left cup to service the bottom bracket. With Fench/Italian BBs the right cup is usually so tight it's not worth even trying (I personally attempted two times but never succeded EDIT. I also managed to damage a Park Tool BB remover, worth 15 quids...)

The left cup is always right threaded, in any case the lockring must have the same thread orientation of the cup.

As for the oversized lockring, I have had a good rate of success using adjustable pliers, just hold them tight enough so to avoid losing grip.

Finally, it's always worth repairing, or at least trying to!