Perhaps Pat or another BBC expert would give their expert opinion as to what the cost would be to have a 2 bolt main upgraded to a 4 bolt main splayed block. A cost of the billet caps as well as the machine work for the 2 bolt block would be appreciated. This would be done to a MK IV 454 and probably be done when the block was bored .060 to convert it over to a 496. I know many people run 2 bolt 496's, but I like rock solid bottom ends. I'm not sure if the MK IV needed to be specially clearanced when it comes to the 496 stroker crank?