It has been said that ZDDP (zinc) is important for valve tappets of this design and vintage. My knowledge is general and not specific to SOHC4 Hondas but in other air-cooled valve tappet machines of this vintage, the cams and rocker arms need the zinc. High ZDDP can be found in certain motor oils. My personal favorite is Valvoline VR1. Or...there are additives which can be used.
Motor oil is something that performance car guys can argue about for many pages.