Gently warm the cast with a propane torch,, not an oxy-acetylene.. then use regular motor oil on the pin,, let it cool,, do it again, let it cool.. each time the cast cools some of the oil will be drawn in as it cools.. I've used this technique many times..
Drilling cast is a bit tricky.. you MUST be on the center of the steel pin.. if your drill wanders, the cast is soft and will cut and drill easier than the pin.. BE carefull, you've got an antique there, you don't want to mess it up..
Since you have to or should take it all apart for resealing with furnace cement anyway, can you get the base separated so you can use a drill press to carefully control the drilling operation??
Wait.. here's an idea.. maybe you don't need to remove the door and do battle with the pins.. first.. is the door flat, that is, is it tight all along the hinge side, or on just one corner? it's possible the cast had some internal stresses that finally 'worked out' from years and from heat/cool cycles.. you may consider useing a belt sander or a hand held grinder, or a Dremel tool, on the hinge side of the door to slowly remove metal at the tight fitting spots, to allow the door to fit at the latch side..
You may not like that idea.. but if the pins are going to be a real pain,, this 'hand fitting' of the door in situ may be the best way.. only a .020" [cardboard thickness] will net you 1/8-1/4" at the latch..
Just something to ponder...
Hope this helps..