Thanks for your message,
It’s a trackstar. This range of stopwatches are referenced in HEUER commercial documentation from the end 70’s (around 1976/1977) to the early 80’s. They feature a 7 jewel pinlever caliber making them a kind of intermediary between classcal lever movement and 1 jewel pinlever movement timers (by example trackmaster).
Yours, the ref. 603.302, is a general purpose stopwatch and your father could have used it to time boxing meetings.
* Here an article with other informations on trackstar timers : https://ikonicstopwatch.com/vintage-stopwatch-heuer-leonidas-ref-652-307-trackstar-allsports/.
* The red. 603.302 is in the 1981 catalog, page 19 : https://ikonicstopwatch.com/1981-heuer-vintage-stopwatch-catalog-iiu-29/.
Regards