I have had 2 cast iron block motors. The 474 was a 400 block with the factory caps and an offset ground factory crank, It had 600 passes and I wore out the cylinders. I had a 440 cast block with aluminum caps that had a 4.375 stroker crank. It had a ton of passes. I put 300 on it and traded it to a guy who ran it to. My opinion since I have ran both is it doesn't matter as long as you have a straight line bore and good crank and the right bearing clearance. Birdtracker