Very Low Oil Pressure in New Engine

makes me wonder if the cam retainer plate has gotten loose?????

I wonder if the cam could walk far enough to uncover the hole in the cam bearing? I guess it would leak enough pressure even if it moved just a little.

solid lifters?

you did not use the dumb bell looking solid lifters?....

Nope. I've only seen those once, odd things and I assume would require the same oiling mods as a roller.