Are you are asking if a Cal. 1866 movement will physically fit in a case made for a regular Speedy? If so, even if it physically fit, how will you adjust the date and moon phase?
@Archer Not to resurrect an old thread... but how technically difficult would it be to drill holes in the case for pusher correctors? A question born out of pure ignorance, but it seems like the obvious follow up...
Holding the case perfectly aligned in the right location would be the tough part. If the angle or location is off slightly then the corrector won't line up with what it has to push.