318's started production with cast cranks for the autos (most of the production numbers) and had a forged version available for some applications like heavy trucks.
Perhaps the machinists/builders who have measured a lot of blocks for cylinder wall thickness will share their observations on older vs later.
My '68 273 block has very little in the way of core shift vs. a much later 360 block. The front and rear walls (non-thrust walls) on the 273 are generally the same thickness as the inner and outer walls (thrust walls) while the 360 has the non-thrust walls thinned out compared to the thrust walls. So perhaps the non-thrust walls were thinned out on later blocks. But that is just a data set of 2 blocks so it not in any way conclusive.
