Was this hero licensed?
Cast Iron rads last and last I have tools that are especially designed to remove AIR VENTS and retap the existing threads.
Air vents replacement is very important as nothing lasts forever ESPECIALLY on steam systems.
Even if the threads are damaged I normally just re drill and retap the threads ONE commerical size larger.
Sight unseen it is hard to second guess BUT in over 33 years of plumbing I yet to find a radiator I couldnt repair other then ones suffering from freeze ups.