Great thread. Im sure this will be useful to other members. Good photos too.
If you don't mind my asking, exactly what type of blasting did you do? You mention bead blasting. You also mention soda blasting. Perhaps you could clarify, did you dry blast, soda blast or vapour blast? They are all different....
Dry blasting is the highest risk of media embedding as its so abrasive. Avoid this. The others are much safer as the vapour softens the impact and sort of peens the surface, although soda blasting is pretty average in the finish it gives. It will come out a matt grey.
As said already, as long as you are meticulous with cleaning and didn't dry blast, it will be fine. Use heat if possible for good measure. Steam cleaning is a good suggestion. I like to use a high pressure water blast too, and use compressed air. Once your finished spritz with oil, WD40, whatever. Also, I disagree with your buddies suggestion that you should blast an assembled engine. No matter how you plug it, under that kind of pressure there is a real risk of media finding a way in that you don't know about and can't clean out.