I replaced one once and did your Option A, drilled through the existing pin
and inserted a metal rod. I used copper because that is what I had on hand.
That said, if I ever had to do it again, I think I would, as an experiment,
take a cue from the way a wristwatch strap is held on. I would try to make
a wooden pin about 1/16 shorter than the plane throat is wide. I would then
drill the pin ends to receive short metal rods of the same diameter as the
original pin end tenons. Drill the holes a little more than twice as deep
as necessary, insert a compression spring, then the metal rods, Then, using
finger pressure on the ends of the metal pins, I would push the pins into
the body of the cross pin, slide it into place, and move it around until
the metal pins seat into the holes in the cheek walls of the plane body.
Again, this is all theoretical but it would be an interesting exercise in