I recently picked up 2 core shortblocks. Both are C5AE-A castings and both have C4AE-B crankshafts. One has C7AE-B rods and the other has C3AE-C rods. One of these engines was a virgin block. It had FoMoCo bearings.

Now these blocks have a casting # that could make it a 390 or a 427. Cross bolt bosses are unmachined. Both blocks are bored to 390 specs. One is standard the other is 0.030 over. I'm trying to determine if these engines can be bored to 427 specs. Has anyone here had experience boring a C5AE-A block to 427 specs?