I built a 408W from all new parts. I soaked the lifters in motor oil for a day. I still can pushdown the plunger on the lifters with my finger. Should they be pumped up with oil prior to setting the valve lash? If so, would running the oil pump with a priming rod and a drill pump them up?
Just soaking them will not help the plunger absorb oil. While they are in oil, push the plunger down with a push rod or something that will force the air out and pull the oil in as the plunger returns.