Mike, your "original" piece looks just like the one on my '51, and suspect it's correct for your hood. You say the spring seat is eaten away on it, but I think that could be fixed by welding on the back side. The new gray one has a problem there as well, as the nut for the latch stem is gone, so that would have to be fixed to use it.
Checking on the parts list for that hood latch panel shows a difference in the 47-55.1 year range between Commercial and Utility meaning smaller trucks and Big Bolts, so maybe that new one came off a big bolt hood.
As far as fixing the original, welding the rust holes would fix it up. I'd try forming a piece of copper to fit in the spring seat to keep from having to grind off burn thru on the spring side.
