I have been using Motorhead Classic in six collector cars for nearly a year now. My mechanic, who is a racing engine builder, recommended it. It isn't as expensive as all that, because I buy 8 gallons at a time, and the price drops to only $12.50 per gallon.
All of the oil companies will tell you "there is plenty of zinc in our oil", even when they are trying to sell you "SM" or "CJ" oil.
Motorhead is the only oil that I know of that is willing to tell you "exactly how much" zinc their oil contains. And it's alot. 1250 ppm is just the minimum they guarantee. Their "typical" figure is 1500 ppm. I have had a sample actually tested, and it was above 1600 ppm. That's up there in Royal Purple and Mercedes Benz territory, but without the big price tag.
BTW Motorhead Oil has a website that explains about the importance of the zinc(www.motorheadoil.com).