[pop66ltd]

fordzilla is correct,most of the 428s as advertised are strokers like the 431 and 445 versions.they have a long stroke so a small overbore to clean up the block is all thats nessesary,the overbore on these are only .030 for a total of 4.080 bore.without a sonic test on the 390 block your taking a serious chance if you intend to bore it .080,not to say it cant be done.unlike the common verity of 390 blocks ie. c6me,c7me versions,the d3te,d4te and most service or ribbed blocks will be able to handle the .080 bore and most even have room for .030 if needed down the road for a rebuild.having sonic tested hundereds of blocks,it becomes clear what type of fe blocks are capable of large over-bore,another good block for large over-bore is the C4AE-A as well as the C3AE-A blocks,most of these also have the nubs cast into the block to make cross bolting an easy task.they make a great block to build a 406 as well as a conventional 428,but should be sonic mapped just as the others before boring,also a sonic map after boring is a good idea,it will confirm the previous test and show error readings resulting from scale inside the coolant areas.week areas are common on all blocks but as long as the thrust side carries enough wall thickness,some thin areas can be forgiven as long as the area is confined to a specifc location in the cylinder wall and does not run the entire length of the wall.that being said if your looking for a budget build this would get you by,but for a good solid build on an engine that you need to last,you would be way better off buying a real 428 block or find a solid D4TE block to start the build with.