The fact that some of your lifters are filled with
oil is not a problem per se. However, IMO, it is impossible to set preload if the lifter won't bleed down. Adding the typical 1/2 to 1 turn from zero lash could actually open the valve, rather than preload the lifter. I had exactly this problem with my Crane hydro roller lifters. I made a little jig and slowly bled them in my bench vise. Slowly. Worked very well, and I was able to set my preload. I strongly discourage you from soaking your lifters in
oil for a prolonged period of time prior to installation as they will fill with
oil and end up non-compressible. It was not fun pulling a freshly installed intake so I could bleed my lifters.
It does beg the question as to what happens under dynamic running conditions. I would guess that the lifters behave properly, otherwise valves would constantly be hanging open and you'd be bleeding compression. Or worse.
phil