OK, putting on my helmet.

I believe once an engine is broken in, high concentrations of ZDDP is not nessesary.
My 1st 2 FB's got 30w Valvoline. Only driven summer months.
67-400/4 spd & 70 RAIII 400 in my 68 FB(then a 455 with the RAIII top end-very high compression with a 150 shot of n2o).
Never had a wear problem.

After 33 years, still use the same 30w in my street car, and VR-1 in my street/strip car.
Tony @ BES rec's VR-1 in all race engines.
Thats all he'l use in his engine builds.