Also, which specifications geometry-wise would I need to order an appropriate replacement?
can you measure your existing fork? once you have the data. then you can shop the numbers.
fork tip, axis of axle to crown race seat. + rake/offset.
mosre accurate with fork out of frame steerer in a V block
to secure it level to the table surface,
then you can measure
the difference between steerer tube center line.
and the axis point at the center of the hub axle
Serrota is in New York, .. hand made premium alloy steel?
Waterford is another US source..
one of the Schwinns is an owner/partner of that firm..
The threadless 1" is easy to cope with.. Top tier headsets
are made Chris King , Campag Etc.
and the shim to use a 9/8" stems on 7/8" steerer tubes are sold.
Are threadless known to be weaker in 1" diameter?
Is the shim much of a problem to deal with?
advantage to steel steerers , they still are butted at the bottom,
just now no threads are cut.
and no prob, the stem pinch bolts squeeze the slotted shim
to grip the steerer tube, just fine..