Brent:
I found the same situation when I disassembled my 427!!
It had been built by a Kirkham sub-contractor who was no longer in business. The lifters had
oil holes and push-rod cups held in with circlips. When I took them apart, NO Plungers!! I don't know if they were built that way, or if they were modified hydraulics.
I switched to hydraulic lifter cam and lifters and stashed the original cam and lifters. I'll have to dig them out and take another look out of curiousity. I'll let you know if I come up with anything interesting.
Ted