When my father was around, I got my traditional 2 bolt Campag seat post extended by joining a same diameter Kalloy
tube seat post ,( that <c>was to be at it's max height line), by fitting the 22.2 top inside machined to fit, the bottom
then welded and machined the bead down.. in his home shop.
those old Campag 2 bolt posts were developed with Brooks saddles (which I use), in mind.
.....