Open up my 400 B block today...

The difference could be this is rebuilt?
(EDIT... Not at TDC by 2*’s.)
It’s very clean in here. First big block I opened up. Are they normally like this clean? The 452 heads are clean as well. 2/08/1.74 valves. IIRC, that’s the size.
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Certainly if they are well maintained. My 331 hemi was horrible on the outside but was the cleanest used engine inside I have ever seen.