I can't quite see it, but I suspect the radiator is the period replacement "honeycomb" radiator.
Rather than made with upper and lower boxes connected by "tubes with fins", the honeycomb is constructed of flat sheets of something (possibly copper) soldered together at the edges to make a closed flat-ish oval, and then bent on a form to make the characteristic "honeycomb" shape when lined up against each other.
The honeycomb radiators at their time were the "cheap replacement" - and actually afforded good cooling - as long as the radiator stayed clean and non-corroded.
The problem is time and situation has not been kind to the honeycomb design. The oval tubes tend to get plugged either from deposits from the water, or even things like mouse turds, and once plugged, the tubes/channels can't be "rodded" as could be done with a more conventional radiator.
Generally a honeycomb once found ineffectual - is a "throw-away." Which more or less outlines its original design conception. Cheap radiator - use it until you can't - then go buy another to replace it.
Which is where you're at now - except the next honeycomb is not available, and I'm not sure anyone is doing "cores" this way.
I don't know for sure as I have not tried them but today's "aluminum" radiators may be the same marketing mode.
There may be a fortunate here in that aluminum is "near" iron in the galvanic series - and probably why aluminum engine blocks seem to survive pretty well even with appended iron connections and parts.
https://en.wikipedia.org/wiki/Galvanic_corrosion
Joe K