replacing antique balance springs

Our Historical Society has several old jewelry store display cases. the access to the cases is through a number of "sashes" on the back of the cases. The sashes are controlled via 10 lb balance springs. We need to replace about 6 of them. Not sure if your parts can be put together to accomplish this. Right now the old balnce springs sit in a recess (like a sash window) Old spring housing is 1 1/8 x 2 3/4" attached via a faceplate (like a door latch) Plate is 1 1/8 x 4 1/2" Do you think we could use your products?

Old springs are "Caldwell Sash Balance". We do not have any part of the non-working items. Photo is of one of the working springs - so we need housing and spring.

thank you