I would recommend trying known to be standard 18-size movements for fit, use caution in this as the case may very well have been made prior to standardization of movement sizes. This experiment could also help determine if it was indeed made for a Howard movement which it may have been. In figuring this out, a picture or two would help along with specific details of all the case-maker markings.
Lindell
Posts: 10553 | Location: Northeastern Ohio in the USA | Registered: November 19, 2002