I have seen several engine blocks over the past few years with porosity issues.
A buddy of mine had a 572 alloy BB chev built and it oozed
oil from all over the place.
The block was impregnated with resin to fill the voids.
I would clean the block with a solvent (carby or brake clean or similar) to rid it of any
oil and then either run it or let it sit and see what happens.