Label me as a picky bugger, but I wouldn't be happy with a crossed-out/re-stamped caliber designation on the barrel, and for a whole lot of reasons. But fundamentally, I think the markings need to be clear and distinct, and without the suggestion of any sort of hocus-pocus or slight-of-hand. You don't want some official somewhere to ask questions about why the original caliber marks were crossed out, then remarked. The less explaining you have to do, the better.

Keep things simple, straight, uncompromising, and to-the-point........even if that means you go with a different rifle for your safari.

AD