good lord. if the rad support is THAT rusted out, chances are a lot of the REST of the chassis is rusty as well.
the rad support is replaceable as long as you have a decent fabricator at your disposal.
http://www.chairslayer.org/products/s13-radsupport
https://thehumbleengineering.com/sho...-nissan-240sx/
there are reinforced ones available too, or you could remove the entire front radiator support and go tube frame, but that's a large amount of fabrication