Delvac MX is a CH/CI rated oil and should have it's level about 1300. It's not limited by the catatonic diverter/particulate trap restriction. CJ oils are limited to 1200 ppm or less. CM to under 900? - can't remember CM off hand.
On the high extreme is Mobil 1 V-Twin which is 1750 ppm. IMHO it's really much ado about nothing from magazines, advertisers, and speculation by armchair experts as back in the 1960s (the good ole days according to the armchair flat tappet cam experts) the zinc content was probably no more than 600 or 700 max. It's not like stock Enfield cams are high lift, heavy spring, high performance cams. The famous GM Additive only brought zinc levels up to 900.