I'm away for the weekend but have filled the down tube with ammonia and will see what happens on Monday.
I'll try clamping the post in the vice and torquing with the frame.
The stem is stuck, too.
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1972 Colnago Super, 1972 Bianchi Specialissima Professionale, 1998 Colnago Monotitan, 2014 Salsa Horsethief, 2015 Salsa Mukluk Ti