Oil in my antifreeze?

[1Madmachinist]

Forgive my ignorance but what’s the best procedure for reverse flushing? My initial idea was to machine an aluminum plate to fit in place of the oil cooler that had fittings on the other side to plug a water hose to then remove the water pump and thermostat and wash everything out through those ports but I tend to over think things. Also I’m not completely sure of how the coolant flows through the block.