How would you stack up the relative merits?
CZ:

-Commercially available, right now;
-Heavier;
-Advantages (theoretical?) of a true magnum action;
-Proprietary/unique parts (e.g., trigger)
-Horrendous stock.

Whitworth:

-Have to hunt up a used one (not too hard);
-Lighter;
-Ready to scope with off-the-shelf mounts;
-Uses many standard Mauser parts/accessories (e.g., Timney trigger);
-Usable stock from the factory.

Anything else?

I like the CZ for its integral scope rails, set trigger, easy bolt take down and nice finish.

The Whitworth (zastava) is disappointing in these same areas. There are better mausers available.

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I have the 550 .416 rigby. What a set trigger is doing on such a rifle is beyond me. For a .375 I would choose a different action with better trigger options.

The CZ also has a drop magazine and holds a fistfull of 375 cartidges.