Here are several oils from back in the day....

(sarcasm: when everything, especially oil, was perfect and nothing ever broke down, ever...Even 305 and 2.3 cams lasted forever!! Just ask anyone who worked on them back then! )

....tested by an independent with a dash of humor thrown in....

http://www.blackstone-labs.com/Newsletters/Gas-Diesel/October-1-2012.php

Notice, some of them don't have diddley squat of the magic elixirs....

Purely based on reading a pile of VOAs and what people who are supposed to know what they are talking about are saying....It won't do any harm to try to get something 1000 PPM ZDDP or slightly higher, by means of the oil itself or an additive. Does this mean 2000 ppm is better? No.

I feel that break in procedure, proper lifter rotation/crown/lobe taper are probably more important than the exact oil formula. Many radical flat tappet cams have been successfully run on nothing more than Walmart supertech 15w40 heavy duty oil, for instance. You can use the fanciest, most expensive oil known to man but if your lifters don't rotate, the oil will not save you.

Mobil 1 15w50 used to be a pretty safe bet, SL was fine, even after SM it was still ok, now it's SN and well below 1000 ppm of the magical stuff, which IMHO is a bit of a confidence killer. The thinner grades are very short on magic additives. That said, I wouldn't be afraid to use it on an already broken in stockish cam with light valve springs.

ps. "zinc" is not the missing link...it's zddp, it's a combination of several things, it is not just zinc.....