Here is a rebuilt/restored American Standard shower valve.
8" from the center of hot handle to the center of cold handle, standard size for mid-century.
Rebuilt, includes seats/stems/packing and after-market chrome trim (looks exactly like the original trim).
While this valve is listed as a "shower" valve...the tee that extends up for the shower could be turned down
to use the valve as a "tub" valve.
This A/Stan valve was manufactured from the mid 1930s to the mid 1950s virtually unchanged for 20 years.