Bore 283
Let me summarize. Can you bore a 283 to 4"? Yes. Have guys done it without sonic testing the block? Yes. Were they lucky? Most were. The purpose of sonic testing is because during machining operations on a new block, there is room for error. You want to call that core shift? Bottom line is if the machined bore is not in the center of the cylinder casting, there most likely will not be enough meat on the short side to allow the motor to survive. So you put the dough in it and then waste all those parts... My solution to that dilemma was to find an old 327 with a small journals, and put the 283 crank in it. Good luck.