Luckily they made thousands of CB750 engines, and many are still around, if often in bits in a shed.
Some one asked about my classic racing in another thread, I started on a Triton with a 1954 T100 500cc engine, with a 'delta' head and cams from the rare Triumph factory race kit. Damn I should have kept that engine. Instead I sold it and bought a 750cc Weslake engine, which, although very fast (140mph), kept breaking different parts of the chassis, often at a bad moment.
If you had a vintage, or classic, bike, that only a handful of still existed, you'd kill for a cam this good. To us, it's scrap. If only whoever stashed it away for a long time had thought to grease the bearing surfaces it first.