That should be a steel case. If not, it is wrong for the watch.
The watch is one of Heuer's former "Economy" chronographs which came with silver or black dials. There were many different iterations of the case and dials, some with tachy scales, some with contrasting subdials. They are a little more difficult to identify than, for example, the Carrera. The asking price for the eBay example seems to me approximately £700-900 optimistic, especially for the silver dial version which typically is less sought-after.
Attached are some images from OnTheDash. Try searching through the Heuer forum there as well as looking through the old catalogues.
