Quite a bit of rust in the bottom of my original unit.
The Ebay-unit was however completely immaculate. Rubber diaphragms in both units were in seemingly great condition. Could not see much wear on the sliding surfaces either.
The push-rod is the only part missing from the e-bay unit, so I'll try to have a local machine shop fabricate a new one.
At the end of this, I'll hopefully have 2 operational brake booster units.