I got my old AD truck radiator recored with a 3 core for $300 - same price as a new 3 core radiator.
Recoring preserves your original overflow top and bottom portion.
Boiling out with or without chemicals never restores them like new - I would just recore or buy new.
Used radiators are a cheap alternative, but all used radiators are clogged to some degree, in my experience.
