Yes, welded in. You need a 22" core radiator with 3 or 4 rows, or a sawzall...
Man, i really dont want to swap the support then. will the bigger radiator bolt right in to my original support without hacking it up?
Define hacking it up.
Will it bolt in with ZERO mods, no.
Will you likely have to drill some new mounting holes, yes.
Will it cool more than the one you have, probably not since the airflow is limited by the core support.
So, you can sawzall a bigger opening in the core support, weld in a new core support, or go with a high efficiency radiator for you application.