thanks. But it didn't answer the other important part of the question -is it possible that one of them can block off the oil feed to the front main bearing? And i can see his point - the thrust plate will go a good way to sealing the ends and especially if using silicone. But the core plugs are there for a reason. I will have to check out another block to see how far into the gallery the oil feed to #1 lies.
Just edited this now to add this: i went and checked another stripped LA block i had - there are two oil feeds to the #1 main and the feed holes are deep enough back from the from the front of the block so that the core plugs i installed will keep them clear. I can see how a deep plug, or one that is pressed in too far though will block the feed hole.