Oil flow problem on initial prime

Hello folks,

Prior to firing our fresh 360 build we brought up oil pressure using a drill motor and hex shaft (intermediate shaft was pulled). Using a SW mechanical gauge we instantly had 80PSI. After a few second we expected to see oil beginning to flow in the rocker shafts but it never appeared.

We uncrewed the gauge and checked flow through the meter hose, we get a good solid stream. Meter put back in place.

With a flashlight we could see plenty of oil puddling up in the lifter valley. We pulled the rocker shafts and tried again, no oil coming up the transfer ports in the head. We've now pulled the heads and no oil coming through the oil passage in the block deck.

What's happened to oil flow to the top end, both sides are experiencing the same problem BTW? It looks like the lifters are fed from passages that supply the #2 and #4 cam bearings as well as the top ends. Or do I have a misguided understanding of the oil routing.

Thanks for any and all help.

Cheers, Mark