maybe someone here can explain this, but back decade ago I rebuilt several later 70's casting 440. upon measure, they had almost no wear in the bore to command an overbore. I am sure the block was just like the earlier casings, so is it the rings??
I have never used a magnum, but I keep reading here as they can have many miles on them, but not enough wear to need an overbore job. of course, other parts needed for carb and mech fuel pump I guess..
I agree with the comment above on the mopar mags, when reading them, ya gotta remember ads pay the bills not subscribers $$$.... I quit reading them 10-12 yrs back, but MA did have some good common lower $ sense rebuild articles.