Arne - Museum is correct and he has a very good memory. I picked up this one from the Far East and I am certain it is original and correct. The case is marked 741603 and if you are familiar with the Heuer reference numbers it correctly houses a Valjoux 7741 movement. I mention the Far East only because I have seen one or two similar pieces available from sellers in that region however this may be just a coincidence. I have attached some pictures of my example. Yours seems to be a combination of parts and the calibre 12 movement and corresponding case do not appear to be correct. The key to this is the absence of "AUTOMATIC CHRONOGRAPH" from the dial. All Heuer watches with Calibre 11 or 12 movements post Chronomatic feature this. It certainly is interesting to see it in that 11630 case.
regards
Paul
www.heuerworld.com