'68 318 to carbed Magnum 5.2: Check my checklist

That's pretty cool, I didn't know that much about that era engine. I'm wondering if putting a matched set of 16 lifters in would help the oiling trouble you're having. Differently sized oil holes maybe? If it gushes oil in one place, it may not build pressure in others. I'm kind of grasping at stuff here, but I think if it were mine I would try all 16 lifters soaked in oil, install pushrods and rockers, and prime and see what happens.