My take on the oiling system crossover tube for the small block

Colder oil temps perhaps? It would be instructive to swap the gauges and see if the lower pressure flows the gauge on the left. Sounds like it would from your last note.
No I had it warmed up. It was hot. :)
But I have the engine pulled out now so I'll update on that plug under the oil sending unit. Should be there. Lol... I hope.