I'm building two 572 engines right now using the World Products "prepped" aluminum blocks. I checked them both before deciding on what machining to do and guess what - nothing, nada, no machining required. Line hone was perfect (+ or - .0005), as was the lifter bushings, block height, sleeves and cap clearances.

I love KB blocks because I have built so many race engines with them including my own TS motor. Never had an issue that Ken didn't take care of. Great company, but if you can't get a KB - the WP block is my choice.