Was unaware the transmission could be shifted with the clutch. This would obviously be by far the least expensive option.
Most of the production would have been with Carter carbs. And Carter had probably 100 times (or more) the dealers compared to Stromberg. The Carter dealer assortment contained one of the solenoids; so, while not inexpensive, they are around.
The Carter solenoid was housed in a metal housing, so physically much more forgiving than the bakelite unit used by Stromberg.
The solenoid was considered an assessory by the commercial carburetor rebuilders; so a rebuild carburetor would NOT have the solenoid. The consumer was to reuse the old solenoid prior to turning in the old core for the exchange value.
Jon.