Think about how different the roads of today are as compared to the past -- these cars took a beating as compared to what we're all used to now.
If that was my frame, I would cut/remove that ugly piece of spring to see what the situation is underneath. The weld job on it is a mess anyway . . . just the best somebody could do with whatever welding equipment and skills the possessed.
Then you will need to fix the issue on the original cross-member and/or replace it. Given that you have things torn down to this level - now is the time to deal with some of the "sins of the past".