I've taken a few sets apart on damaged beyond repair bbls to salvage the rib extension piece.

Nothing fancy to salvage the part. Acetylene and red heat.
Brazed together or hard soldered. Lots of heat in any case.

Not just Parker, but the other names too.
I'm sure there's some that are not, maybe the early Ithacas(?).

Maybe any soft solder seen along it's seam with the bbl is overlap from when the ribs themselves were soldered in place.