You have a very collectible piece, and not just because of the sentimental attachment to your dad.
The Combat Magnum began at serial number K260001, and many tens of thousands followed. Yours is one of the first 1000. Those early guns such as yours are generally very well finished with a deep, rich blue and mechanically superb.
Yours is a "keeper" for several reasons. Thanks for sharing the history and pictures of a magnificent revolver.

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John