How does a 454 block.. ,casting# 14015445, ... generally rate concerning wall thickness and core shift? I'm new to BB's Thanks

Pretty much average. Should go to .060 easily. any more than that and you should have it sonic checked. As for core shift, check to see how well centered the cam is in the bosses as the front and back of the block and how well centered the lifters are in their bosses. It's not always accurate, but if neither are even close to centered, chances are good that it has a good bit of core shift. You can sure ease your mind by having it sonic checked - then you'll know exactly how much cylinder wall you'll have after boring.