I took my radiator to be serviced by a radiator place. They took it apart & it was obvious that it had passed its use-by date with the corrosion & blockages, so I had a new core fitted.
I made sure I fitted a cheezecloth condom filter into the top tank [it goes in the top rad hose fitting, then fold over it & is held in place by the hose.]
This ensured that the rubbish from the block was not going to block my new core, & sure enough, the amount of junk it has trapped is amazing.
A very good investment I thought, both the new core & the filter & I've never regretted the few extra dollars that it all cost.