I think all the early blocks where the Mega blocks that didn't like to be bored much over 4.410
Maybe someone on here will know when the first World cast iron replacement blocks started entering the Mopar inventory
One of the local racers had several of those early Mopar Mega blocks that had cracked at 4.500 but lived at 4.410 to 4.440 bore sizes
I would have it sonic tested before boring it any bigger