Early 360 blocks

They used the same casting molds and cores as the 340s, yes. So, theoretically, they should be able to go as large in terms of bore sizes as a 340..4.10 max as opposed to 4.06 max. The problem is core shift. If a block is sonic checked, you can see that there are a ton of inconsistencies in the wall's overall thickness. A "thinwall" later casting may be thick enough to bore larger, while some 340 may not have enough meat to safely go more than .030 over themselves. You dont know until you look. There is no "definate" with anything Mopar..